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Z-Shell Frequently Asked Questions (monthly posting)
- From: Peter Stephenson <pws@xxxxxxxxxxxxxxxxx>
- To: zsh-announce@xxxxxxxxxxxxxxx
- Subject: Z-Shell Frequently Asked Questions (monthly posting)
- Date: Mon, 26 Oct 1998 11:09:02 +0100
Archive-Name: unix-faq/shell/zsh
Last-Modified: 1998/10/26
Submitted-By: pws@xxxxxxxxxxxxxx (Peter Stephenson)
Version: $Id: zshfaq.yo,v 1.31 1998/10/26 09:43:13 pws Exp $
Frequency: Monthly
Copyright: (C) P.W. Stephenson, 1995, 1996, 1997, 1998 (see end of document)
Changes since issue posted September 1998:
2.1 Another `typeset' difference turned up.
5.4 Slight addition to Y2K item (prompt formatting)
This document contains a list of frequently-asked (or otherwise
significant) questions concerning the Z-shell, a command interpreter
for many UNIX systems which is freely available to anyone with FTP
access. Zsh is among the most powerful freely available Bourne-like
shell for interactive use.
If you have never heard of `sh', `csh' or `ksh', then you are
probably better off to start by reading a general introduction to UNIX
rather than this document.
If you just want to know how to get your hands on the latest version,
skip to question 1.6; if you want to know what to do with
insoluble problems, go to 5.2.
Notation: Quotes `like this' are ordinary textual quotation
marks. Other uses of quotation marks are input to the shell.
Contents:
Chapter 1: Introducing zsh and how to install it
1.1. Sources of information
1.2. What is it?
1.3. What is it good at?
1.4. On what machines will it run? (Plus important compilation notes)
1.5. What's the latest version?
1.6. Where do I get it?
1.7. I don't have root access: how do I make zsh my login shell?
Chapter 2: How does zsh differ from...?
2.1. sh and ksh?
2.2. csh?
2.3. Why do my csh aliases not work? (Plus other alias pitfalls.)
2.4. tcsh?
2.5. bash?
2.6. Shouldn't zsh be more/less like ksh/(t)csh?
Chapter 3: How to get various things to work
3.1. Why does `$var' where `var="foo bar"' not do what I expect?
3.2. What is the difference between `export' and the ALL_EXPORT option?
3.3. How do I turn off spelling correction/globbing for a single command?
3.4. How do I get the meta key to work on my xterm?
3.5. How do I automatically display the directory in my xterm title bar?
3.6. How do I make the completion list use eight bit characters?
3.7. Why do the cursor (arrow) keys not work?
3.8. Why does my terminal act funny in some way?
3.9. Why does zsh not work in an Emacs shell mode any more?
3.10. Why do my autoloaded functions not autoload [the first time]?
3.11. How does base arithmetic work?
3.12. How do I get a newline in my prompt?
3.13. Why does `bindkey ^a command-name' or 'stty intr ^-' do something funny?
3.14. Why can't I bind \C-s and \C-q any more?
3.15. How do I execute command `foo' within function `foo'?
3.16. Why do history substitutions with single bangs do something funny?
3.17. Why does zsh kill off all my background jobs when I logout?
3.18. How do I list all my history entries?
3.19. How does the alternative loop syntax, e.g. `while {...} {...}' work?
3.20. Why is my history not being saved?
Chapter 4: The mysteries of completion
4.1. What is completion?
4.2. What sorts of things can be completed?
4.3. How does zsh deal with ambiguous completions?
4.4. How do I complete in the middle of words / just what's before the cursor?
4.5. How do I get started with programmable completion?
4.6. And if programmable completion isn't good enough?
Chapter 5: The future of zsh
5.1. What bugs are currently known and unfixed? (Plus recent important changes)
5.2. Where do I report bugs, get more info / who's working on zsh?
5.3. What's on the wish-list?
5.4. Will zsh have problems in the year 2000?
Acknowledgments
Copyright
--- End of Contents ---
Chapter 1: Introducing zsh and how to install it
1.1: Sources of information
Information on zsh is available via the World Wide Web. The URL
is http://sunsite.auc.dk/zsh/ (note the change of address from the
end of April 1998). The server provides this FAQ and much else and is
now maintained by Karsten Thygesen and others (mail zsh@xxxxxxxxxxxxxx
with any related messages). The FAQ is at http://sunsite.auc.dk/zsh/FAQ/ .
The site also contains some contributed zsh scripts and functions;
we are delighted to add more, or simply links to your own collection.
This document was originally written in YODL, allowing it to be
converted easily into various other formats. The master source
file lives at http://sunsite.auc.dk/zsh/FAQ/zshfaq.yo .
Another useful source of information is the collection of FAQ articles
posted frequently to the Usenet news groups comp.unix.questions,
comp.unix.shells and comp.answers with answers to general questions
about UNIX. The fifth of the seven articles deals with shells,
including zsh, with a brief description of differences. (This article
also talks about shell startup files which would otherwise rate a
mention here.) There is also a separate FAQ on shell differences
and how to change your shell. Usenet FAQs are available via FTP
from rtfm.mit.edu and mirrors and also on the World Wide Web; see
USA http://www.cis.ohio-state.edu/hypertext/faq/usenet/top.html
UK http://www.lib.ox.ac.uk/internet/news/faq/comp.unix.shell.html
Netherlands http://www.cs.ruu.nl/wais/html/na-dir/unix-faq/shell/.html
The latest version of this FAQ is also available directly from any
of the zsh archive sites listed in question 1.6.
There is now a preliminary version of a reference card for
zsh 3.0, which you can find (while it's being developed) at
http://www.ifh.de/~pws/computing/refcard.ps
This is optimised for A4 paper. The LaTeX source is in the
same place with the extension .tex. It is not a good place
from which to learn zsh for the first time.
(As a method of reading the following in Emacs, you can type \M-2
\C-x $ to make all the indented text vanish, then \M-0 \C-x $
when you are on the title you want.)
For any more eclectic information, you should contact the mailing
list: see question 5.2.
1.2: What is it?
Zsh is a UNIX command interpreter (shell) which of the standard
shells most resembles the Korn shell (ksh); its compatibility with
the 1988 Korn shell has been gradually increasing. It includes
enhancements of many types, notably in the command-line editor,
options for customising its behaviour, filename globbing, features
to make C-shell (csh) users feel more at home and extra features
drawn from tcsh (another `custom' shell).
It was written by Paul Falstad when a student at Princeton; however,
Paul doesn't maintain it any more and enquiries should be sent to
the mailing list (see question 5.2). Zsh is distributed under a
standard Berkeley style copyright.
For more information, the files Doc/intro.txt or Doc/intro.troff
included with the source distribution are highly recommended. A list
of features is given in FEATURES, also with the source.
1.3: What is it good at?
Here are some things that zsh is particularly good at. No claim of
exclusivity is made, especially as shells copy one another, though
in the areas of command line editing and globbing zsh is well ahead
of the competition. I am not aware of a major interactive feature
in any other freely-available shell which zsh does not also have
(except smallness).
o Command line editing:
o programmable completion: incorporates the ability to use
the full power of zsh globbing (compctl -g),
o multi-line commands editable as a single buffer (even files!),
o variable editing (vared),
o command buffer stack,
o print text straight into the buffer for immediate editing (print -z),
o execution of unbound commands,
o menu completion,
o variable, editing function and option name completion,
o inline expansion of variables, history commands.
o Globbing --- extremely powerful, including:
o recursive globbing (cf. find),
o file attribute qualifiers (size, type, etc. also cf. find),
o full alternation and negation of patterns.
o Handling of multiple redirections (simpler than tee).
o Large number of options for tailoring.
o Path expansion (=foo -> /usr/bin/foo).
o Adaptable messages for spelling, watch, time as well as prompt
(including conditional expressions).
o Named directories.
o Comprehensive integer arithmetic.
o Manipulation of arrays (including reverse subscripting).
o Spelling correction.
1.4: On what machines will it run?
From version 3.0, zsh uses GNU autoconf as the installation
mechanism. This considerably increases flexibility over the old
`buildzsh' mechanism. Consequently, zsh should compile and run on
any modern version of UNIX, and a great many not-so-modern versions
too. The file Etc/MACHINES in the distribution has more details.
There are also now separate ports for Windows and OS/2, see `Where
do I get it' below.
If you need to change something to support a new machine, it would be
appreciated if you could add any necessary preprocessor code and
alter configure.in and config.h.in to configure zsh automatically,
then send the required context diffs to the list (see question
5.2). Changes based on version 2.5 are very unlikely to
be useful.
To get it to work, retrieve the source distribution (see question
1.6), un-gzip it, un-tar it and read the INSTALL file in the top
directory. Also read the Etc/MACHINES file for up-to-date
information on compilation on certain architectures.
*Note for users of nawk* (The following information comes from Zoltan
Hidvegi): On some systems nawk is broken and produces an incorrect
signames.h file. This makes the signals code unusable. This often happens
on Ultrix, HP-UX, IRIX (?). Install gawk if you experience such problems.
1.5: What's the latest version?
Zsh 3.0.5 is the latest production version. The new major number 3.0
largely reflects the considerable internal changes in zsh to make it
more reliable, consistent and (where possible) compatible. Those
planning on upgrading their zsh installation should take a look at
the list of incompatibilities at the end of 5.1. This is
longer than usual due to enhanced sh, ksh and POSIX compatibility.
The beta version 3.1.4 is also available. Development of zsh is
usually patch by patch, with each intermediate version publicly
available. Note that this `open' development system does mean bugs
are sometimes introduced into the most recent archived version.
These are usually fixed quickly.
Note also that as the shell changes, it may become incompatible with
older versions; see the end of question 5.1 for a partial list.
Changes of this kind are almost always forced by an awkward or
unnecessary feature in the original design (as perceived by current
users), or to enhance compatibility with other Bourne shell
derivatives, or (most recently) to provide POSIX compliancy.
1.6: Where do I get it?
The archive is now run by Andrew Main <zefram@xxxxxxxxx>.
The following are known mirrors (kept frequently up to date); the
first is the official archive site, currently in Australia. All are
available by anonymous FTP. The major sites keep test versions in
the 'testing' subdirectory: such up-to-the-minute development
versions should only be retrieved if you actually plan to help test
the latest version of the shell. The following list also appears
on the WWW at http://www.zsh.org .
Home site ftp://ftp.zsh.org
Australia ftp://ftp.ips.gov.au/mirror/zsh/
Denmark ftp://sunsite.auc.dk/pub/unix/shells/zsh
Finland ftp://ftp.funet.fi/pub/unix/shells/zsh/
France ftp://ftp.cenatls.cena.dgac.fr/pub/shells/zsh/
Germany ftp://ftp.fu-berlin.de/pub/unix/shells/zsh/
ftp://ftp.gmd.de/packages/zsh/
ftp://ftp.uni-trier.de/pub/unix/shell/zsh/
Hungary ftp://ftp.cs.elte.hu/pub/zsh/
(also http://www.cs.elte.hu/pub/zsh/ )
Israel ftp://ftp.math.technion.ac.il/mirror/ftp.zsh.org/pub/zsh/
http://www.math.technion.ac.il/mirror/ftp.zsh.org/pub/zsh/
Japan ftp://ftp.tohoku.ac.jp/mirror/zsh/
ftp://ftp.nis.co.jp/pub/shells/zsh/
Norway ftp://ftp.uit.no/pub/unix/shells/zsh/
Romania ftp://ftp.roedu.net/pub/mirrors/ftp.zsh.org/pub/zsh/
Slovenia ftp://ftp.siol.net/pub/unix/shells/zsh/
Sweden ftp://ftp.lysator.liu.se/pub/unix/zsh/
UK ftp://ftp.net.lut.ac.uk/zsh/
(also by FSP at port 21)
ftp://src.doc.ic.ac.uk/packages/unix/shells/zsh/
USA ftp://ftp.math.gatech.edu/pub/zsh/
ftp://uiarchive.uiuc.edu/pub/packages/shells/zsh/
ftp://ftp.sterling.com/zsh/
ftp://ftp.rge.com/pub/shells/zsh/
The Windows port mentioned above is maintained separately by Amol
Deshpande <amold@xxxxxxxxxxxxx>; please mail Amol directly about any
Windows-specific problems. This is quite new, so don't expect it to
be perfect. You can get it from:
ftp://ftp.blarg.net/users/amol/zsh
Likewise the OS/2 port is available from TAMURA Kent
<kent@xxxxxxxxxxxxxx> at
http://cgi.din.or.jp/~tkent/tmp/zsh-3.0.0-os2-a01.zip
Starting from mid-October 1997, there is an archive of patches sent
to the maintainers' mailing list. Note that these may not all be
added to the shell, and some may already have been; you simply have
to search for something you might want which is not in the version
you have. Also, there may be some prerequisites earlier in the
archive. It can be found on the zsh WWW pages (as described in
1.1) at:
http://sunsite.auc.dk/zsh/Patches/
1.7: I don't have root access: how do I make zsh my login shell?
Unfortunately, on many machines you can't use `chsh' to change your
shell unless the name of the shell is contained in /etc/shells, so if
you have your own copy of zsh you need some sleight-of-hand to use it
when you log on. (Simply typing `zsh' is not really a solution since
you still have your original login shell waiting for when you exit.)
The basic idea is to use `exec <zsh-path>' to replace the current
shell with zsh. Often you can do this in a login file such as .profile
(if your shell is sh or ksh) or .login (if it's csh). Make sure you
have some way of altering the file (e.g. via FTP) before you try this as
`exec' is often rather unforgiving.
If you have zsh in a subdirectory `bin' of your home directory,
put this in .profile:
[ -f $HOME/bin/zsh ] && exec $HOME/bin/zsh -l
or if your login shell is csh or tcsh, put this in .login:
if ( -f ~/bin/zsh ) exec ~/bin/zsh -l
(in each case the `-l' tells zsh it is a login shell).
If you want to check this works before committing yourself to it,
you can make the login shell ask whether to exec zsh. The following
work for Bourne-like shells:
[ -f $HOME/bin/zsh ] && {
echo "Type Y to run zsh: \c"
read line
[ "$line" = Y ] && exec $HOME/bin/zsh -l
}
and for C-shell-like shells:
if ( -f ~/bin/zsh ) then
echo -n "Type Y to run zsh: "
if ( "$<" == Y ) exec ~/bin/zsh -l
endif
It's not a good idea to put this (even without the -l) into .cshrc,
at least without some tests on what the csh is supposed to be doing,
as that will cause _every_ instance of csh to turn into a zsh and
will cause csh scripts (yes, unfortunately some people write these)
which do not call `csh -f' to fail. If you want to tell xterm to
run zsh, change the SHELL environment variable to the full path of
zsh at the same time as you exec zsh (in fact, this is sensible for
consistency even if you aren't using xterm). If you have to exec
zsh from your .cshrc, a minimum safety check is `if ($?prompt) exec
zsh'.
If you like your login shell to appear in the process list as `-zsh',
you can link `zsh' to `-zsh' (e.g. by `ln -s ~/bin/zsh
~/bin/-zsh') and change the exec to `exec -zsh'. (Make sure
`-zsh' is in your path.) This has the same effect as the `-l'
option.
Footnote: if you DO have root access, make sure zsh goes in
/etc/shells on all appropriate machines, including NIS clients, or you
may have problems with FTP to that machine.
Chapter 2: How does zsh differ from...?
As has already been mentioned, zsh is most similar to ksh, while many
of the additions are to please csh users. Here are some more detailed
notes. See also the article `UNIX shell differences and how to change
your shell' posted frequently to the USENET group comp.unix.shell.
2.1: Differences from sh and ksh
Most features of ksh (and hence also of sh) are implemented in zsh;
problems can arise because the implementation is slightly different.
Note also that not all ksh's are the same either. I have based this
on the 11/16/88f version of ksh; differences from ksh93 will be more
substantial.
As a summary of the status:
1) because of all the options it is not safe to assume a general
zsh run by a user will behave as if sh or ksh compatible;
2) invoking zsh as sh or ksh (or if either is a symbolic link to
zsh) sets appropriate options and improves compatibility (from
within zsh itself, calling `ARGV0=sh zsh' will also work);
3) from version 3.0 onward the degree of compatibility with sh
under these circumstances is very high: zsh can now be used
with GNU configure or perl's Configure, for example;
4) the degree of compatibility with ksh is also high, but a few
things are missing: for example the more sophisticated
pattern-matching expressions are different for versions before
3.1.3 --- see the detailed list below;
5) also from 3.0, the command `emulate' is available: `emulate
ksh' and `emulate sh' set various options as well as changing the
effect of single-letter option flags as if the shell had been
invoked with the appropriate name. Including the commands
`emulate sh; setopt localoptions' in a shell function will
turn on sh emulation for that function only.
The classic difference is word splitting, discussed in 3.1; this
catches out very many beginning zsh users. As explained there, this
is actually a bug in every other shell. The answer is to set
SH_WORD_SPLIT for backward compatibility. The next most classic
difference is that unmatched glob patterns cause the command to
abort; set NO_NOMATCH for those.
Here is a list of various options which will increase ksh
compatibility, though maybe decrease zsh's abilities: see the manual
entries for GLOB_SUBST, IGNORE_BRACES (though brace expansion occurs
in some versions of ksh), KSH_ARRAYS, KSH_GLOB, KSH_OPTION_PRINT,
LOCAL_OPTIONS, NO_BAD_PATTERN, NO_BANG_HIST, NO_EQUALS, NO_HUP,
NO_NOMATCH, NO_RCS, NO_SHORT_LOOPS, PROMPT_SUBST, RM_STAR_SILENT,
POSIX_BUILTINS, SH_FILE_EXPANSION, SH_GLOB, SH_OPTION_LETTERS,
SH_WORD_SPLIT (see question 3.1) and SINGLE_LINE_ZLE.
Note that you can also disable any built-in commands which get in
your way. If invoked as `ksh', the shell will try and set suitable
options.
Here are some differences from ksh which might prove significant for
ksh programmers, some of which may be interpreted as bugs; there
must be more. Note that this list is deliberately rather full and
that most of the items are fairly minor. Those marked `*' perform
in a ksh-like manner if the shell is invoked with the name `ksh', or
if `emulate ksh' is in effect. Capitalised words with underlines
refer to shell options.
o Syntax:
o * Shell word splitting: see question 3.1.
o * Arrays are (by default) more csh-like than ksh-like:
subscripts start at 1, not 0; array[0] refers to array[1];
`$array' refers to the whole array, not $array[0];
braces are unnecessary: $a[1] == ${a[1]}, etc.
The KSH_ARRAYS option is now available.
o Coprocesses are established by `coproc'; `|&' behaves like
csh. Handling of coprocess file descriptors is also different.
o In `cmd1 && cmd2 &', only `cmd2' instead of the whole
expression is run in the background in zsh. The manual implies
this is a bug. Use `{ cmd1 && cmd2 } &' as a workaround.
o Command line substitutions, globbing etc.:
o * Failure to match a globbing pattern causes an error (use
NO_NOMATCH).
o * The results of parameter substitutions are treated as plain text:
`foo="*"; print $foo' prints all files in ksh but `*' in zsh.
(GLOB_SUBST has been added to fix this.)
o The backslash in $(echo '\$x') is treated differently: in ksh, it
is not stripped, in zsh it is. (The `...` form gives the same in
both shells.)
o * $PSn do not do parameter substitution by default (use PROMPT_SUBST).
o * Standard globbing does not allow ksh-style `pattern-lists'.
Equivalents:
----------------------------------------------------------------------
ksh zsh Meaning
----- ----- ---------
!(foo) ^foo Anything but foo.
or foo1~foo2 Anything matching foo1 but foo2[1].
@(foo1|foo2|...) (foo1|foo2|...) One of foo1 or foo2 or ...
?(foo) (foo|) Zero or one occurrences of foo.
*(foo) (foo)# Zero or more occurrences of foo.
+(foo) (foo)## One or more occurrences of foo.
----------------------------------------------------------------------
The `^', `~' and `#' (but not `|')forms require EXTENDED_GLOB.
From version 3.1.3, the ksh forms are fully supported when the
option KSH_GLOB is in effect; for previous versions you
must use the table above.
[1] Note that `~' is the only globbing operator to have a lower
precedence than `/'. For example, `**/foo~*bar*' matches any
file in a subdirectory called `foo', except where `bar'
occurred somewhere in the path (e.g. `users/barstaff/foo' will
be excluded by the `~' operator). As the `**' operator cannot
be grouped (inside parentheses it is treated as `*'), this is
the way to exclude some subdirectories from matching a `**'.
o Unquoted assignments do file expansion after `:'s (intended for
PATHs).
o `integer' does not allow `-i'.
o `typeset' and `integer' have special behaviour for
assignments in ksh, but not in zsh. For example, this doesn't
work in zsh:
integer k=$(wc -l ~/.zshrc)
because the return value from wc includes leading
whitespace which causes wordsplitting. Ksh handles the
assignment specially as a single word.
o Command execution:
o * There is no $ENV variable (use /etc/zshrc, ~/.zshrc;
note also $ZDOTDIR).
o $PATH is not searched for commands specified
at invocation without -c.
o Aliases and functions:
o The order in which aliases and functions are defined is significant:
function definitions with () expand aliases -- see question 2.3.
o Aliases and functions cannot be exported.
o There are no tracked aliases: command hashing replaces these.
o The use of aliases for key bindings is replaced by `bindkey'.
o * Options are not local to functions (use LOCAL_OPTIONS; note this
may always be unset locally to propagate options settings from a
function to the calling level).
o Traps and signals:
o Traps are not local to functions.
o TRAPERR has become TRAPZERR (this was forced by UNICOS which
has SIGERR).
o Editing:
o The options emacs, gmacs, viraw are not supported.
Use bindkey to change the editing behaviour: `set -o {emacs,vi}'
becomes `bindkey -{e,v}'; for gmacs, go to emacs mode and use
`bindkey \^t gosmacs-transpose-characters'.
o The `keyword' option does not exist and `-k' is instead
interactivecomments. (`keyword' will not be in the next ksh
release either.)
o Management of histories in multiple shells is different:
the history list is not saved and restored after each command.
o `\' does not escape editing chars (use `^V').
o Not all ksh bindings are set (e.g. `<ESC>#'; try `<ESC>q').
o * `#' in an interactive shell is not treated as a comment by
default.
o Built-in commands:
o Some built-ins (r, autoload, history, integer ...)
were aliases in ksh.
o There is no built-in command newgrp: use e.g. `alias
newgrp="exec newgrp"'
o `jobs' has no `-n' flag.
o `read' has no `-s' flag.
o Other idiosyncrasies:
o `select' always redisplays the list of selections on each loop.
2.2: Similarities with csh
Although certain features aim to ease the withdrawal symptoms of csh
(ab)users, the syntax is in general rather different and you should
certainly not try to run scripts without modification. The c2z script
is provided with the source (in Misc/c2z) to help convert .cshrc
and .login files; see also the next question concerning aliases,
particularly those with arguments.
Csh-compatibility additions include:
o logout, rehash, source, (un)limit built-in commands.
o *rc file for interactive shells.
o Directory stacks.
o cshjunkie*, ignoreeof options.
o The CSH_NULL_GLOB option.
o >&, |& etc. redirection.
(Note that `>file 2>&1' is the standard Bourne shell command for
csh's `>&file'.)
o foreach ... loops; alternative syntax for other loops.
o Alternative syntax `if ( ... ) ...', though this still doesn't
work like csh: it expects a command in the parentheses. Also
`for', `which'.
o $PROMPT as well as $PS1, $status as well as $?,
$#argv as well as $#, ....
o Escape sequences via % for prompts.
o Special array variables $PATH etc. are colon-separated, $path
are arrays.
o !-type history (which may be turned off via `setopt
nobanghist').
o Arrays have csh-like features (see under 2.1).
2.3: Why do my csh aliases not work? (Plus other alias pitfalls.)
First of all, check you are using the syntax
alias newcmd='list of commands'
and not
alias newcmd 'list of commands'
which won't work. (It tells you if `newcmd' and `list of commands' are
already defined as aliases.)
Otherwise, your aliases probably contain references to the command
line of the form `\!*', etc. Zsh does not handle this behaviour as it
has shell functions which provide a way of solving this problem more
consistent with other forms of argument handling. For example, the
csh alias
alias cd 'cd \!*; echo $cwd'
can be replaced by the zsh function,
cd() { builtin cd $*; echo $PWD; }
(the `builtin' tells zsh to use its own `cd', avoiding an infinite loop)
or, perhaps better,
cd() { builtin cd $*; print -D $PWD; }
(which converts your home directory to a ~). In fact, this problem is
better solved by defining the special function chpwd() (see the manual).
Note also that the `;' at the end of the function is optional in zsh,
but not in ksh or sh (for sh's where it exists).
Here is Bart Schaefer's guide to converting csh aliases for zsh.
1) If the csh alias references "parameters" (\!:1, \!* etc.),
then in zsh you need a function (referencing $1, $* etc.).
Otherwise, you can use a zsh alias.
2) If you use a zsh function, you need to refer _at_least_ to
$* in the body (inside the { }). Parameters don't magically
appear inside the { } the way they get appended to an alias.
3) If the csh alias references its own name (alias rm "rm -i"),
then in a zsh function you need the "command" keyword
(function rm() { command rm -i $* }), but in a zsh alias
you don't (alias rm="rm -i").
4) If you have aliases that refer to each other (alias ls "ls -C";
alias lf "ls -F" ==> lf == ls -C -F) then you must either:
o convert all of them to zsh functions; or
o after converting, be sure your .zshrc defines all of your
aliases before it defines any of your functions.
Those first four are all you really need, but here are four more for
heavy csh alias junkies:
5) Mapping from csh alias "parameter referencing" into zsh function
(assuming shwordsplit and ksharrays are NOT set in zsh):
csh zsh
===== ==========
\!* $* (or $argv)
\!^ $1 (or $argv[1])
\!:1 $1
\!:2 $2 (or $argv[2], etc.)
\!$ $*[$#] (or $argv[$#], or $*[-1])
\!:1-4 $*[1,4]
\!:1- $*[1,$#-1] (or $*[1,-2])
\!^- $*[1,$#-1]
\!*:q "$@" ($*:q doesn't work (yet))
\!*:x $=* ($*:x doesn't work (yet))
6) Remember that it is NOT a syntax error in a zsh function to
refer to a position ($1, $2, etc.) greater than the number of
parameters. (E.g., in a csh alias, a reference to \!:5 will
cause an error if 4 or fewer arguments are given; in a zsh
function, $5 is the empty string if there are 4 or fewer
parameters.)
7) To begin a zsh alias with a - (dash, hyphen) character, use
`alias --':
csh zsh
=============== ==================
alias - "fg %-" alias -- -="fg %-"
8) Stay away from `alias -g' in zsh until you REALLY know what
you're doing.
There is one other serious problem with aliases: consider
alias l='/bin/ls -F'
l() { /bin/ls -la $* | more }
`l' in the function definition is in command position and is expanded
as an alias, defining `/bin/ls' and `-F' as functions which call
`/bin/ls', which gets a bit recursive. This can be avoided if you use
`function' to define a function, which doesn't expand aliases. It is
possible to argue for extra warnings somewhere in this mess. Luckily,
it is not possible to define `function' as an alias.
Bart Schaefer's rule is: Define first those aliases you expect to
use in the body of a function, but define the function first if the
alias has the same name as the function.
2.4: Similarities with tcsh
(The sections on csh apply too, of course.) Certain features have
been borrowed from tcsh, including $watch, run-help, $savehist,
$histlit, periodic commands etc., extended prompts, sched
and which built-ins. Programmable completion was inspired by,
but is entirely different to, tcsh's `complete'. (There is a perl
script called lete2ctl in the Misc directory of the source
distribution to convert `complete' to `compctl' statements.)
This list is not definitive: some features have gone in the other
direction.
If you're missing the editor function run-fg-editor, try something
with `bindkey -s' (which binds a string to a keystroke), e.g.
bindkey -s '^z' '\eqfg %$EDITOR:t\n'
which pushes the current line onto the stack and tries to bring a job
with the basename of your editor into the foreground. `bindkey -s'
allows limitless possibilities along these lines. You can execute
any command in the middle of editing a line in the same way,
corresponding to tcsh's `-c' option:
bindkey -s '^p' '\eqpwd\n'
In both these examples, the `\eq' saves the current input line to
be restored after the command runs; a better effect with multiline
buffers is achieved if you also have
bindkey '\eq' push-input
to save the entire buffer.
2.5: Similarities with bash
The Bourne-Again Shell, bash, is another enhanced Bourne-like shell;
the most obvious difference from zsh is that it does not attempt to
emulate the Korn shell. Since both shells are under active
development it is probably not sensible to be too specific here.
Broadly, bash has paid more attention to standards compliancy
(i.e. POSIX) for longer, and has so far avoided the more abstruse
interactive features (programmable completion, etc.) that zsh has.
2.6: Shouldn't zsh be more/less like ksh/(t)csh?
People often ask why zsh has all these `unnecessary' csh-like features,
or alternatively why zsh doesn't understand more csh syntax. This is
far from a definitive answer and the debate will no doubt continue.
Paul's object in writing zsh was to produce a ksh-like shell which
would have features familiar to csh users. For a long time, csh was
the preferred interactive shell and there is a strong resistance to
changing to something unfamiliar, hence the additional syntax and
CSH_JUNKIE options. This argument still holds. On the other hand,
the arguments for having what is close to a plug-in replacement for ksh
are, if anything, even more powerful: the deficiencies of csh as a
programming language are well known (look in any Usenet FAQ archive, e.g.
http://www.cis.ohio-state.edu/hypertext/faq/usenet/unix-faq/\
shell/csh-whynot/faq.html
if you are in any doubt) and zsh is able to run many standard
scripts such as /etc/rc.
Of course, this makes zsh rather large and feature-ridden so that it
seems to appeal mainly to hackers. The only answer, perhaps not
entirely satisfactory, is that you have to ignore the bits you don't
want. The introduction of loadable in modules in version 3.1 should
help.
Chapter 3: How to get various things to work
3.1: Why does `$var' where `var="foo bar"' not do what I expect?
In most Bourne-shell derivatives, multiple-word variables such as
var="foo bar"
are split into words when passed to a command or used in a `for foo in
$var' loop. By default, zsh does not have that behaviour: the
variable remains intact. (This is not a bug! See below.) An option
(SHWORDSPLIT) exists to provide compatibility.
For example, defining the function args to show the number of its
arguments:
args() { echo $#; }
and with our definition of `var',
args $var
produces the output `1'. After
setopt shwordsplit
the same function produces the output `2', as with sh and ksh.
Unless you need strict sh/ksh compatibility, you should ask yourself
whether you really want this behaviour, as it can produce unexpected
effects for variables with entirely innocuous embedded spaces. This
can cause horrendous quoting problems when invoking scripts from
other shells. The natural way to produce word-splitting behaviour
in zsh is via arrays. For example,
set -A array one two three twenty
(or
array=(one two three twenty)
if you prefer), followed by
args $array
produces the output `4', regardless of the setting of SHWORDSPLIT.
Arrays are also much more versatile than single strings. Probably
if this mechanism had always been available there would never have
been automatic word splitting in scalars, which is a sort of
uncontrollable poor man's array.
Note that this happens regardless of the value of the internal field
separator, $IFS; in other words, with `IFS=:; foo=a:b; args $foo'
you get the answer 1.
Other ways of causing word splitting include a judicious use of
`eval':
sentence="Longtemps, je me suis couch\\'e de bonne heure."
eval "words=($sentence)"
after which $words is an array with the words of $sentence (note
characters special to the shell, such as the `'' in this example,
must already be quoted), or, less standard but more reliable,
turning on SHWORDSPLIT for one variable only:
args ${=sentence}
always returns 8 with the above definition of `args'. (In older
versions of zsh, ${=foo} toggled SHWORDSPLIT; now it forces it on.)
Note also the "$@" method of word splitting is always available in zsh
functions and scripts (though strictly this does array splitting, not
word splitting).
SHWORDSPLIT is set when zsh is invoked with the names `ksh' or `sh',
or (entirely equivalent) when `emulate ksh' or `emulate sh' is in
effect.
3.2: What is the difference between `export' and the ALL_EXPORT option?
Normally, you would put a variable into the environment by using
`export var'. The command `setopt allexport' causes all
variables which are subsequently set (N.B. not all the ones which
already exist) to be put into the environment.
This may seem a useful shorthand, but in practice it can have
unhelpful side effects:
1) Since every variable is in the environment as well as remembered
by the shell, the memory for it needs to be allocated twice.
This is bigger as well as slower.
2) It really is *every* variable which is exported, even loop
variables in `for' loops. This is probably a waste.
3) An arbitrary variable created by the user might have a special
meaning to a command. Since all shell variables are visible to
commands, there is no protection against this.
For these reasons it is usually best to avoid ALL_EXPORT unless you
have a specific use for it. One safe use is to set it before
creating a list of variables in an initialisation file, then unset
it immediately afterwards. Only those variables will be automatically
exported.
3.3: How do I turn off spelling correction/globbing for a single command?
In the first case, you presumably have `setopt correctall' in an
initialisation file, so that zsh checks the spelling of each word in
the command line. You probably do not want this behaviour for
commands which do not operate on existing files.
The answer is to alias the offending command to itself with
`nocorrect' stuck on the front, e.g.
alias mkdir='nocorrect mkdir'
To turn off globbing, the rationale is identical:
alias mkdir='noglob mkdir'
You can have both nocorrect and noglob, if you like, but the
nocorrect must come first, since it is needed by the line editor,
while noglob is only handled when the command is examined.
Note also that a shell function won't work: the no... directives must
be expanded before the rest of the command line is parsed.
3.4: How do I get the meta key to work on my xterm?
As stated in the manual, zsh needs to be told about the meta key by
using `bindkey -me' or `bindkey -mv' in your .zshrc or on the
command line. You probably also need to tell the terminal driver to
allow the `meta' bit of the character through; `stty pass8' is the
usual incantation. Sample .zshrc entry:
[[ $TERM = "xterm" ]] && stty pass8 && bindkey -me
or, on SYSVR4-ish systems without pass8,
[[ $TERM = "xterm" ]] && stty -parenb -istrip cs8 && bindkey -me
(disable parity detection, don't strip high bit, use 8-bit characters).
Make sure this comes _before_ any bindkey entries in your .zshrc which
redefine keys normally defined in the emacs/vi keymap.
You don't need the `bindkey' to be able to define your own sequences
with the meta key, though you still need the `stty'.
3.5: How do I automatically display the directory in my xterm title bar?
You should use the special function `chpwd', which is called when
the directory changes. The following checks that standard output is
a terminal, then puts the directory in the title bar if the terminal
is an xterm or a sun-cmd.
chpwd() {
[[ -t 1 ]] || return
case $TERM in
sun-cmd) print -Pn "\e]l%~\e\\"
;;
xterm) print -Pn "\e]2;%~\a"
;;
esac
}
Change `%~' if you want the message to be different. (The `-P'
option interprets such sequences just like in prompts, in this case
producing the current directory; you can of course use `$PWD' here,
but that won't use the `~' notation which I find clearer.) Note that
when the xterm starts up you will probably want to call chpwd
directly: just put `chpwd' in .zshrc after it is defined or autoloaded.
3.6: How do I make the completion list use eight bit characters?
A traditional UNIX environment (character terminal and ASCII
character sets) is not sufficient to be able to handle non-ASCII
characters, and there are so many possible enhancements that in
general this is hard. However, if you have something like an xterm
using a standard character set like ISO-8859-1 (which is often the
default for xterm), read on. You should also note question
3.4 on the subject of eight bit characters.
You are probably creating files with names including non-ASCII
accented characters, and find they show up in the completion list as
\M-i or something such. This is because the library routines
(not zsh itself) which test whether a character is printable have
replied that it is not; zsh has simply found a way to show them
anyway.
The answer, under a modern POSIXy operating system, is to find a
locale where these are treated as printable characters. Zsh has
handling for locales built in and will recognise when you set a
relevant variable. You need to look in /usr/lib/locale to find one
which suits you; the subdirectories correspond to the locale names.
The simplest possibility is likely to be en_US, so that the simplest
answer to your problem is to set
LC_CTYPE=en_US
when your terminal is capable of showing eight bit characters. If
you only have a default domain (called C), you may need to have some
additional files installed on your system.
3.7: Why do the cursor (arrow) keys not work?
The cursor keys send different codes depending on the terminal; zsh
only binds the most well known versions. If you see these problems,
try putting the following in your .zshrc:
bindkey "$(echotc kl)" backward-char
bindkey "$(echotc kr)" forward-char
bindkey "$(echotc ku)" up-line-or-history
bindkey "$(echotc kd)" down-line-or-history
If you use vi mode, use `vi-backward-char' and `vi-forward-char'
where appropriate.
Note, however, that up to version 3.0 binding arbitrary multiple key
sequences can cause problems, so check that this works with your set
up first. Also, from version 3.1.3, more sequences are supported by
default, namely those in the form `<ESC>O' followed by A,
B, C or D, as well as the corresponding set beginning
`<ESC>[', so this may be redundant.
3.8: Why does my terminal act funny in some way?
If you are using an OpenWindows cmdtool as your terminal, any
escape sequences (such as those produced by cursor keys) will be
swallowed up and never reach zsh. Either use shelltool or avoid
commands with escape sequences. You can also disable scrolling from
the cmdtool pane menu (which effectively turns it into a shelltool).
If you still want scrolling, try using an xterm with the scrollbar
activated.
If that's not the problem, and you are using stty to change some tty
settings, make sure you haven't asked zsh to freeze the tty settings:
type
ttyctl -u
before any stty commands you use.
On the other hand, if you aren't using stty and have problems you may
need the opposite: `ttyctl -f' freezes the terminal to protect it
from hiccups introduced by other programmes (kermit has been known to
do this).
If _that_'s not the problem, and you are having difficulties with
external commands (not part of zsh), and you think some terminal
setting is wrong (e.g. ^V is getting interpreted as `literal next
character' when you don't want it to be), try
ttyctl -u
STTY='lnext "^-"' commandname
(in this example), or just export STTY for all commands to see. Note
that zsh doesn't reset the terminal completely afterwards: just the
modes it uses itself and a number of special processing characters
(see the stty(1) manual page).
At some point there may be an overhaul which allows the terminal
modes used by the shell to be modified separately from those seen by
external programmes. This is partially implemented already: from 2.5,
the shell is less susceptible to mode changes inherited from
programmes than it used to be.
3.9: Why does zsh not work in an Emacs shell mode any more?
(This information comes from Bart Schaefer and other zsh-workers.)
Emacs 19.29 or thereabouts stopped using a terminal type of "emacs"
in shell buffers, and instead sets it to "dumb". Zsh only kicks in
its special I'm-inside-emacs initialization when the terminal type
is "emacs".
Probably the most reliable way of dealing with this is to look for
the environment variable `$EMACS', which is set to `t' in
Emacs' shell mode. Putting
[[ $EMACS = t ]] && unsetopt zle
in your .zshrc should be sufficient.
Another method is to put
#!/bin/sh
TERM=emacs exec zsh
into a file ~/bin/eshell, then `chmod +x ~/bin/eshell', and
tell emacs to use that as the shell by adding
(setenv "ESHELL" "~/bin/eshell")
to ~/.emacs.
3.10: Why do my autoloaded functions not autoload [the first time]?
The problem is that there are two possible ways of autoloading a
function (see the AUTOLOADING FUNCTIONS section of the zsh manual
page zshmisc for more detailed information):
1) The file contains just the body of the function, i.e.
there should be no line at the beginning saying `function foo {'
or `foo () {', and consequently no matching `}' at the end.
This is the traditional zsh method. The advantage is that the
file is called exactly like a script, so can double as both.
To define a function `xhead () { print -n "\033]2;$*\a"; }',
the file would just contain `print -n "\033]2;$*\a"'.
2) The file contains the entire definition, and maybe even
other code: it is run when the function needs to be loaded, then
the function itself is called up. This is the method in ksh.
To define the same function `xhead', the whole of the
usual definition should be in the file.
In old versions of zsh, before 3.0, only the first behaviour was
allowed, so you had to make sure the file found for autoload just
contained the function body. You could still define other functions
in the file with the standard form for definitions, though they
would be redefined each time you called the main function.
In version 3.0.x, the second behaviour is activated if the file
defines the autoloaded function. Unfortunately, this is
incompatible with the old zsh behaviour which allowed you to
redefine the function when you called it.
From version 3.1, there is an option KSHAUTOLOAD to allow full ksh
compatiblity, i.e. the function _must_ be in the second form
above. If that is not set, zsh tries to guess which form you are
using: if the file contains only a complete definition of the
function in the second form, and nothing else apart from comments
and whitespace, it will use the function defined in the file;
otherwise, it will assume the old behaviour. The option is set
if `emulate ksh' is in effect, of course.
(A neat trick to autoload all functions in a given directory is to
include a line like `autoload ~/fns/*(:t)' in .zshrc; the bit in
parentheses removes the directory part of the filenames, leaving
just the function names.)
3.11: How does base arithmetic work?
The ksh syntax is now understood, i.e.
let 'foo = 16#ff'
or equivalently
(( foo = 16#ff ))
or even
foo=$[16#ff]
(note that `foo=$((16#ff))' is now supported). The original syntax was
(( foo = [16]ff ))
--- this was based on a misunderstanding of the ksh manual page. It
still works but its use is deprecated. Then
echo $foo
gives the answer `255'. It is possible to declare variables explicitly
to be integers, via
typeset -i foo
which has a different effect: namely the base used in the first
assignment (hexadecimal in the example) is subsequently used whenever
`foo' is displayed (although the internal representation is unchanged).
To ensure foo is always displayed in decimal, declare it as
typeset -i 10 foo
which requests base 10 for output. You can change the output base of an
existing variable in this fashion. Using the `$(( ... ))' method will
always display in decimal.
3.12: How do I get a newline in my prompt?
You can place a literal newline in quotes, i.e.
PROMPT="Hi Joe,
what now?%# "
If you have the bad taste to set the option cshjunkiequotes, which
inhibits such behaviour, you will have to bracket this with
`unsetopt cshjunkiequotes' and `setopt cshjunkiequotes', or put it
in your .zshrc before the option is set.
Arguably the prompt code should handle `print'-like escapes. Feel
free to write this :-). Otherwise, you can use
PROMPT=$(print "Hi Joe,\nwhat now?%# ")
in your initialisation file.
3.13: Why does `bindkey ^a command-name' or `stty intr ^-' do something funny?
You probably have the extendedglob option set in which case ^ and #
are metacharacters. ^a matches any file except one called a, so the
line is interpreted as bindkey followed by a list of files. Quote the
^ with a backslash or put quotation marks around ^a.
3.14: Why can't I bind \C-s and \C-q any more?
The control-s and control-q keys now do flow control by default,
unless you have turned this off with `stty -ixon' or redefined the
keys which control it with `stty start' or `stty stop'. (This is
done by the system, not zsh; the shell simply respects these
settings.) In other words, \C-s stops all output to the terminal,
while \C-q resumes it.
There is an option NO_FLOW_CONTROL to stop zsh from allowing flow
control and hence restoring the use of the keys: put `setopt
noflowcontrol' in your .zshrc file.
3.15: How do I execute command `foo' within function `foo'?
The command `command foo' does just that. You don't need this with
aliases, but you do with functions. Note that error messages like
zsh: job table full or recursion limit exceeded
are a good sign that you tried calling `foo' in function `foo' without
using `command'. If `foo' is a builtin rather than an external
command, use `builtin foo' instead.
3.16: Why do history substitutions with single bangs do something funny?
If you have a command like "echo !-2:$ !$", the first history
substitution then sets a default to which later history substitutions
with single unqualified bangs refer, so that !$ becomes equivalent to
!-2:$. The option CSH_JUNKIE_HISTORY makes all single bangs refer
to the last command.
3.17: Why does zsh kill off all my background jobs when I logout?
Simple answer: you haven't asked it not to. Zsh (unlike [t]csh) gives
you the option of having background jobs killed or not: the `nohup'
option exists if you don't want them killed. Note that you can always
run programs with `nohup' in front of the pipeline whether or not the
option is set, which will prevent that job from being killed on
logout. (`nohup' is actually an external command.)
The `disown' builtin is very useful in this respect: if zsh informs
you that you have background jobs when you try to logout, you can
`disown' all the ones you don't want killed when you exit. This is
also a good way of making jobs you don't need the shell to know about
(such as commands which create new windows) invisible to the shell.
Likewise, you can start a background job with `&!' instead of just
`&' at the end, which will automatically disown the job.
3.18: How do I list all my history entries?
Tell zsh to start from entry 1: `history 1'. Those entries at the
start which are no longer in memory will be silently omitted.
3.19: How does the alternative loop syntax, e.g. `while {...} {...}' work?
Zsh provides an alternative to the traditional sh-like forms with `do',
while TEST; do COMMANDS; done
allowing you to have the COMMANDS delimited with some other command
structure, often `{...}'. The rules are quite complicated and
in most scripts it is probably safer --- and certainly more
compatible --- to stick with the sh-like rules. If you are
wondering, the following is a rough guide.
To make it work you must make sure the TEST itself is clearly
delimited. For example, this works:
while (( i++ < 10 )) { echo i is $i; }
but this does _not_:
while let "i++ < 10"; { echo i is $i; } # Wrong!
The reason is that after `while', any sort of command list is valid.
This includes the whole list `let "i++ < 10"; { echo i $i; }';
the parser simply doesn't know when to stop. Furthermore, it is
wrong to miss out the semicolon, as this makes the `{...}' part
of the argument to `let'. A newline behaves the same as a
semicolon, so you can't put the brace on the next line as in C.
So when using this syntax, the test following the `while' must
be wrapped up: any of `((...))', `[[...]]', `{...}' or
`(...)' will have this effect. (They have their usual syntactic
meanings too, of course; they are not interchangeable.) Note that
here too it is wrong to put in the semicolon, as then the case
becomes identical to the preceding one:
while (( i++ < 10 )); { echo i is $i; } # Wrong!
The same is true of the `if' and `until' constructs:
if { true } { echo yes } else { echo no }
but with `for', which only needs a list of words, you can get
away with it:
for foo in a b; { echo foo is $a; bar=$foo; }
since the parser knows it only needs everything up to the first
semicolon. For the same reason, there is no problem with the `repeat',
`case' or `select' constructs; in fact, `repeat' doesn't even
need the semicolon since it knows the repeat count is just one word.
This is independent of the behaviour of the SHORTLOOPS option (see
manual), which you are in any case encouraged even more strongly not
to use in programs as it can be very confusing.
3.20: Why is my history not being saved?
In zsh, you need to set three variables to make sure your history is
written out when the shell exits. For example,
HISTSIZE=200
HISTFILE=~/.zsh_history
SAVEHIST=200
$HISTSIZE tells the shell how many lines to keep internally,
$HISTFILE tells it where to write the history, and $SAVEHIST,
the easiest one to forget, tells it how many to write out. The
simplest possibility is to set it to the same as $HISTSIZE as
above. There are also various options affecting history; see the
manual.
Chapter 4: The mysteries of completion
Programmable completion using the `compctl' command is one of the most
powerful, and also potentially confusing, features of zsh; here I give
a short introduction. There is a set of example completions supplied
with the source in Misc/compctl-examples; completion definitions for
many of the most obvious commands can be found there.
4.1: What is completion?
`Completion' is where you hit a particular command key (TAB is the
standard one) and the shell tries to guess the word you are typing
and finish it for you --- a godsend for long file names, in
particular, but in zsh there are many, many more possibilities than
that.
There is also a related process, `expansion', where the shell sees
you have typed something which would be turned by the shell into
something else, such as a variable turning into its value ($PWD
becomes /home/users/mydir) or a history reference (!! becomes
everything on the last command line). In zsh, when you hit TAB it
will look to see if there is an expansion to be done; if there is,
it does that, otherwise it tries to perform completion. (You can
see if the word would be expanded --- not completed --- by TAB by
typing `\C-x g', which lists expansions.) Expansion is generally
fairly intuitive and not under user control; for the rest of the
chapter I will discuss completion only.
4.2: What sorts of things can be completed?
The simplest sort is filename completion, mentioned above. Unless
you have made special arrangements, as described below, then after
you type a command name, anything else you type is assumed by the
completion system to be a filename. If you type part of a word and
hit TAB, zsh will see if it matches the first part a file name and
if it does it will automatically insert the rest.
The other simple type is command completion, which applies
(naturally) to the first word on the line. In this case, zsh
assumes the word is some command to be executed lying in your $PATH
(or something else you can execute, like a builtin command, a
function or an alias) and tries to complete that.
Other forms of completion have to be set up by special arrangement.
See the manual entry for compctl for a list of all the flags: you
can make commands complete variable names, user names, job names,
etc., etc.
For example, one common use is that you have an array variable,
$hosts, which contains names of other machines you use frequently on
the network:
hosts=(fred.ph.ku.ac.uk snuggles.floppy-bunnies.com here.there.edu)
then you can tell zsh that when you use telnet (or ftp, or ...), the
argument will be one of those names:
compctl -k hosts telnet ftp ...
so that if you type `telnet fr' and hit TAB, the rest of the name
will appear by itself.
An even more powerful option to compctl (-g) is to tell zsh that
only certain sorts of filename are allowed. The argument to -g is
exactly like a glob pattern, with the usual wildcards `*', `?', etc.
In the compctl statement it needs to be quoted to avoid it being
turned into filenames straight away. For example,
compctl -g '*.(ps|eps)' ghostview
tells zsh that if you type TAB on an argument after a ghostview
command, only files ending in `.ps' or `.eps' should be considered
for completion.
A useful addition for zsh from version 3.1 is directory completion:
compctl -/ cd
Before, you had to use -g, but this is neater: it takes care of
things like ignoring directories beginning with a dot unless you've
typed the dot yourself, and whole directory paths are understood.
Note that flags may be combined; if you have more than one, all the
possible completions for all of them are put into the same list, all
of them being possible completions. So
compctl -k hosts -f rcp
tells zsh that rcp can have a hostname or a filename after it. (You
really need to be able to handle host:file, which is where
programmable completion comes in, see 4.5.) Also, from
version 3.1 you can always handle directories at the same time as
other files just by adding -/ to the list.
4.3: How does zsh deal with ambiguous completions?
Often there will be more than one possible completion: two files
start with the same characters, for example. Zsh has a lot of
flexibility for what it does here via its options. The default is
for it to beep and completion to stop until you type another
character. You can type \C-D to see all the possible completions.
(That's assuming your at the end of the line, otherwise \C-D will
delete the next character and you have to use ESC-\C-D.) This can be
changed by the following options, among others:
o with nobeep set, that annoying beep goes away
o with nolistbeep, beeping is only turned off for ambiguous completions
o with autolist set, when the completion is ambiguous you get a
list without having to type \C-D
o with listambigous, this is modified so that nothing is listed if
there is an unambiguous prefix or suffix to be inserted
o with menucomplete set, one completion is always inserted
completely, then when you hit TAB it changes to the next, and so
on until you get back to where you started
o with automenu, you only get the menu behaviour when you hit TAB
again on the ambiguous completion.
o Finally, although it affects all completion lists, including
those explicitly requested, note also alwayslastprompt, which
causes the cursor to return to the line you were editing after
printing the list, provided that is short enough.
Combinations of these are possible; for example, autolist and
automenu together give an intuitive combination. Note that
from version 3.1 listambiguous is set by default; if you use
autolist, you may well want to `unsetopt listambiguous'.
4.4: How do I complete in the middle of words / just what's before the cursor?
Sometimes you have a word on the command-line (let's stick to file
names) which is incomplete in the middle. Normally if you hit tab
in zsh, it will simply go to the end of the word and try to complete
there. However, there are two ways of changing this.
First, there is the option COMPLETE_IN_WORD. This tries to fill in
the word at the point of the cursor. For example, if the current
directory contains `foobar', then with the option set, you can
complete `fbar' to `foobar' by moving the cursor to the
`b' and hitting tab.
That's not the full story, however. Sometimes you just want the
part of the word before the cursor completed. For example, the word
is `/usr/loc/b', which you want to complete to `/usr/local/bin'.
Normally, zsh won't do this in one go because there are two bits
missing (but see below!), so you need to complete the `/usr/loc'
on its own first. For this you need the function
expand-or-complete-prefix: it works mostly like the usual
function bound to tab, but it ignores anything on the right of the
cursor. If you always want this behaviour (some other shells do
this), bind it to tab; otherwise put another binding, e.g. `^X
TAB' in ~/.zshrc:
bindkey "^X^I" expand-or-complete-prefix
then in the example you can move to just after `/usr/loc', hit
whatever key you've just bound, move to the end, and hit tab.
(Note that AUTO_REMOVE_SLASH behaviour applies here, see the manual.)
Even that doesn't exhaust the possibilities. Included with the
source distribution is the file Functions/multicomp, a function
which you can bind as an alternative form of default completion (see
below for a description of alternative completion), e.g.
compctl -D -f + -U -Q -K multicomp
and whole sequences of directories, like `/usr/loc/b' or even
`/u/l/b' can be completed in one go. It works best with
menucompletion if the result is ambiguous.
4.5: How do I get started with programmable completion?
Finally, the hairiest part of completion. It is possible to get zsh
to consider different completions not only for different commands,
but for different words of the same command, or even to look at
other words on the command line (for example, if the last word was a
particular flag) and decide then.
There are really two sorts of things to worry about. The simpler is
alternative completion: that just means zsh will try one
alternative, and only if there are no possible completions try the
next. For example
compctl -g '*.ps' + -f lpr
says that after lpr you'd prefer to find only `.ps' files, so if
there are any, only those are used, but if there aren't any, any
old file is a possibility. You can also have a + with no flags
after it, which tells zsh that it's to treat the command like any
other if nothing was found. That's only really useful if your
default completion is fancy, i.e. you have done something with
`compctl -D' to tell zsh how commands which aren't specially handled
are to have their arguments completed.
The second sort is the hard one. Following a `-x', zsh expects that
the next thing will be some completion code, which is a single
letter followed by an argument in square brackets. For example
`p[1]': `p' is for position, and the argument tells it to look at
position 1; that says that this completion only applies to the word
immediately after the command. You can also say `p[1,3]' which says
the completion only applies to the word if it's between the first
and third words, inclusive, after the command, and so on. See the
list in the `compctl' manual entry for a list of these conditions:
some conditions take one argument in the square brackets, some two.
Usually, negative numeric arguments count backwards from the end
(for example, `p[-1]' applies to the last word on the line).
(Note the difference in the ways `+' and `-x' work. A `+'
completion will always try and find completions for what's before
the `+' first; it will only produce a list for what's after if
the first list was empty. On the other hand, if a condition for a
`-x' matches, the appropriate set of completions is always used,
even if the list of completions produced is empty.)
The condition is then followed by the flags as usual (as in 4.2),
and possibly other condition/flag sets following a single -; the
whole lot ends with a double -- before the command name. In other
words, each extended completion section looks like this:
-x <pattern> <flags>... [ - <pattern> <flags>... ...] --
Let's look at rcp again: this assumes you've set up $hosts as above.
This uses the `n[<n>,<string>]' flag, which tells zsh to look for
the <n>'th occurrence of <string> in the word, ignoring anything up
to and including that. We'll use it for completing the bits of
rcp's `user@host:file' combination. (Of course, the file name is on
the local machine, not `host', but let's ignore that; it may still
be useful.)
compctl -k hosts -S ':' + -f -x 'n[1,:]' -f - \
'n[1,@]' -k hosts -S ':' -- rcp
This means: (1) try and complete a hostname (the bit before the
`+'), if successful add a `:' (-S for suffix); (2) if that fails
move on to try the code after the `+': look and see if there is a
`:' in a word (the `n[1,:]'); if there is, complete filenames
(-f) after the first of them; (3) otherwise look for an `@' and
complete hostnames after the first of them (the `n[1,@]'), adding a
`:' if successful; (4) if all else fails use the `-f' before the
`-x' and try to complete files.
So the rules for order are (1) try anything before a `+' before
anything after it (2) try the conditions after a -x in order until
one succeeds (3) use the default flags before the -x if none of the
conditions was true.
Different conditions can also be combined. There are three levels
of this (in decreasing order of precedence):
1) multiple square brackets after a single condition give
alternatives: for example, `s[foo][bar]' says apply the
completion if the word begins with `foo' or `bar',
2) spaces between conditions mean both must match: for example,
`p[1] s[-]' says this completion only applies for the first word
after the command and only if it begins with a `-',
3) commas between conditions mean either can match: for example,
`c[-1,-f], s[-f]' means either the previous word (-1 relative to
the current one) is -f, or the current word begins with -f ---
useful to use the same completion whether or not the -f has a
space after it.
You must be careful to put the whole expression inside quotation
marks, so that it appears as a single argument to compctl.
Here's a useless example just to show a general `-x' completion.
compctl -f -x 'c[-1,-u][-1,-U] p[2], s[-u]' -u - \
'c[-1,-j]' -P % -j -- foobar
The way to read this is: for command `foobar', look and see if (((the
word before the current one is -u) or (the word before the current
one is -U)) and (the current word is 2)) or (the current word begins
with -u); if so, try to complete user names. If the word before
the current one is -j, insert the prefix `%' before the current word
if it's not there already and complete job names. Otherwise, just
complete file names.
4.6: And if programmable completion isn't good enough?
...then your last resort is to write a shell function to do it for
you. By combining the `-U' and `-K func' flags you can get
almost unlimited power. The `-U' tells zsh that whatever the
completion produces is to be used, even if it doesn't fit what's
there already (so that gets deleted when the completion is
inserted). The `-K func' tells zsh a function name. The
function is passed the part of the word already typed, and can read
the rest of the line with `read -c'. It can return a set of
completions via the `reply' array, and this becomes the set of
possible completions. The best way to understand this is to look at
`multicomp' and other functions supplied with the zsh
distribution.
Chapter 5: The future of zsh
5.1: What bugs are currently known and unfixed? (Plus recent important changes)
Here are some of the more well-known ones, very roughly in
decreasing order of significance. Many of these can also be counted
against differences from ksh in question 2.1; note that this applies
to the latest beta version and that simple bugs are often fixed
quite quickly. There is a file Etc/BUGS in the source distribution
with more detail.
o `time' is ignored with builtins and can't be used with `{...}'.
o `set -x' (`setopt xtrace') still has a few glitches.
o Zsh's notion of the current line number (via $LINENO) is
sometimes not well handled, particularly when using functions and traps.
o In vi mode, `u' can go past the original modification point.
o The singlelinezle option has problems with prompts containing escapes.
o The `r' command does not work inside `$(...)' or ``...`'
expansions. (This is fixed in 3.1.)
o `typeset' handling is non-optimal, particularly with regard to
flags, and is ksh-incompatible in unpredictable ways.
o Nested closures in extended globbing and pattern matching, such as
[[ fofo = (fo#)# ]]
were not correctly handled, and there were problems with
complicated exclusions using `^' or `~'. (These
are fixed in version 3.1.3.)
Note that a few recent changes introduce incompatibilities (these
are not bugs):
Changes after zsh 3.0 (3.1.x is still currently in beta):
o The options ALWAYS_LAST_PROMPT (return to the line you were
editing after displaying completion lists) and LIST_AMBIGUOUS
(show matching files when there are several) are now set by
default. This is in response to complaints that too many zsh
features are never noticed by many users. To turn them off,
just put `unsetopt alwayslastprompt listambiguous' in your
.zshrc file.
o history-search-{forward,backward} now only find previous
lines where the first word is the same as the current one. For
example,
comp<ESC>p
will find lines in the history like `comp -edit emacs', but not
`compress file' any more. For this reason, `\M-n' and
`\M-p' use history-beginning-search-{forward,backward} which
search for a line with the same prefix up to the cursor position.
It is possible to write functions which go a little closer to the
original behaviour; further changes are still possible.
o In vi insert mode, the cursor keys no longer work. The following
will bind them:
bindkey -M viins '^[[D' vi-backward-char '^[[C' vi-forward-char \
'^[[A' up-line-or-history '^[[B' down-line-or-history
(unless your terminal requires `^[O' instead of `^[['). The
rationale is that the insert mode and command mode keymaps for
keys with prefixes are now separate.
Changes since zsh 2.5:
o The left hand of an assignment is no longer substituted. Thus,
`$1=$2' will not work. You can use something like `eval
"$1=\$2"', which should have the identical effect.
o Signal traps established with the `trap' builtin are now called with
the environment of the caller, as in ksh, instead of as a new
function level. Traps established as functions (e.g. `TRAPINT()
{...}') work as before.
o The NO_CLOBBER option is now -C and PRINT_EXIT_VALUE -1; they used
to be the other way around. (Use of names rather than letters is
generally recommended.)
o `[[' is a reserved word, hence must be separated from
other characters by whitespace; `{' and `}' are also reserved
words if the IGNORE_BRACES option is set.
o The option CSH_JUNKIE_PAREN has been removed: csh-like code now
always does what it looks like it does, so `if ( ... ) ...'
executes the code in parentheses in a subshell. To make this
useful, the syntax expected after an `if', etc., is less strict
than in other shells.
o `foo=*' does not perform globbing immediately on the right
hand side of the assignment; the old behaviour now requires the
option GLOB_ASSIGN. (`foo=(*)' is and has always been the
consistent way of doing this.)
o <> performs redirection of input and output to the specified file.
For numeric globs, you now need <->.
o The command line qualifiers exec, noglob, command, - are now
treated more like builtin commands: previously they were
syntactically special. This should make it easier to perform
tricks with them (disabling, hiding in parameters, etc.).
o The pushd builtin has been rewritten for compatibility with other
shells. The old behavour can be achieved with a shell function.
o The current version now uses ~'s for directory stack substitution
instead of ='s. This is for consistency: all other directory
substitution (~user, ~name, ~+, ...) used a tilde, while
=<number> caused problems with =program substitution.
o The `HISTLIT' option was broken in various ways and has been removed:
the rewritten history mechanism doesn't alter history lines, making
the option unnecessary.
o History expansion is disabled in single-quoted strings, like other
forms of expansion -- hence exclamation marks there should not be
backslashed.
o The `$HISTCHARS' variable is now `$histchars'. Currently both
are tied together for compatibility.
o The PROMPT_SUBST option now performs backquote expansion -- hence
you should quote these in prompts. (SPROMPT has changed as a result.)
o Quoting in prompts has changed: close parentheses inside ternary
expressions should be quoted with a %; history is now %!, not
!. Backslashes are no longer special.
5.2: Where do I report bugs, get more info / who's working on zsh?
The shell is being maintained by various (entirely self-appointed)
subscribers to the mailing list,
zsh-workers@xxxxxxxxxxxxxxx
so mail on any issues (bug reports, suggestions, complaints...)
related to the development of the shell should be sent there. If
you want someone to mail you directly, say so. Most patches to zsh
appear there first.
Please note when reporting bugs that many exist only on certain
architectures, which the developers may not have access to. In
this case debugging information, as detailed as possible, is
particularly welcome.
Two progressively lower volume lists exist, one with messages
concerning the use of zsh,
zsh-users@xxxxxxxxxxxxxxx
and one just containing announcements: about releases, about major
changes in the shell, or this FAQ, for example,
zsh-announce@xxxxxxxxxxxxxxx
(posting to the last one is currently restricted).
Note that you should only join one of these lists: people on
zsh-workers receive all the lists, and people on zsh-users will
also receive the announcements list.
The lists are handled by an automated server. The instructions for
zsh-announce and zsh-users are the same as for zsh-workers: just
change zsh-workers to whatever in the following.
To join zsh-workers, send email to
zsh-workers-request@xxxxxxxxxxxxxxx
with the *subject* line (this is a change from the old list)
subscribe <your-email-address>
e.g.
Subject: subscribe P.Stephenson@xxxxxxxxxxxxx
and you can unsubscribe in the same way.
The list maintainer, Richard Coleman, can be reached at
coleman@xxxxxxxxxxxxxxx.
The list from May 1992 to May 1995 is archived in
ftp://ftp.sterling.com/zsh/zsh-list/YY-MM
where YY-MM are the year and month in digits. More recent
mailings up to date are to be found at
http://www.zsh.org/mla/
at the main zsh archive in Australia.
Of course, you can also post zsh queries to the Usenet group
comp.unix.shell; if all else fails, you could even e-mail me.
5.3: What's on the wish-list?
With version 3, the code is much cleaner than before, but still
bears the marks of the ages and many things could be done much
better with a rewrite. A more efficient set of code for
lexing/parsing/execution might also be an advantage. Volunteers are
particularly welcome for these tasks.
An improved line editor, with user-definable functions and binding
of multiple functions to keystrokes, is being developed.
o Loadable module support (will be in 3.1 but much work still needs doing).
o Ksh compatibility could be improved.
o Option for glob qualifiers to follow perl syntax (a traditional item).
o Binding of shell functions to key strokes, accessing editing
buffer from functions, executing zle functions as a command: now
under development for 3.1.
o Users should be able to create their own foopath/FOOPATH array/path
combinations.
5.4: Will zsh have problems in the year 2000?
(This information was written by Bart Schaefer. Note it is a
description of the state of affairs as seen by the developers, it is
not a guarantee!)
You can confirm the following by looking at the source code yourself
if necessary; there's no other definitive reference:
Zsh uses UNIX/POSIX time_t, timeval, and tm data types for internal
date manipulations. These types either do not store year values at
all (for example, time_t is measured in seconds since midnight, Jan
1, 1970) or store them as integer types and NOT as pairs of digits.
Thus there can be no overflows at year 2000. On some unix systems,
time_t is a 32-bit value and will overflow during the year 2038, but
more modern systems use a 64-bit time_t.
The only input and output of dates that zsh performs for its own use
is optional history time-stamping. This is performed using time_t
values converted to long integers, which are either 32 or 64 bits,
see above.
Note, however, that zsh does provide facilities for formatted date
output, in particular in prompt escapes such as `%W' and
`%D' using `print -P', so it's possible that scripts written
for zsh might employ 2-digit years. Shell scripts should always be
considered separate programs and therefore evaluated individually.
Acknowledgments:
Thanks to zsh-list, in particular Bart Schaefer, for suggestions
regarding this document. Zsh has been in the hands of archivists Jim
Mattson, Bas de Bakker, Richard Coleman, Zoltan Hidvegi and Andrew
Main, and the mailing list has been run by Peter Gray, Rick Ohnemus
and Richard Coleman, all of whom deserve thanks. The world is
eternally in the debt of Paul Falstad for inventing zsh in the first
place (though the wizzo extended completion is by Sven Wischnowsky).
Copyright Information:
This document is copyright (C) P.W. Stephenson, 1995, 1996, 1997,
1998. This text originates in the U.K. and the author asserts his
moral rights under the Copyrights, Designs and Patents Act, 1988.
Permission is hereby granted, without written agreement and without
license or royalty fees, to use, copy, modify, and distribute this
documentation for any purpose, provided that the above copyright
notice appears in all copies of this documentation. Remember,
however, that this document changes monthly and it may be more useful
to provide a pointer to it rather than the entire text. A suitable
pointer is "information on the Z-shell can be obtained on the World
Wide Web at URL http://sunsite.auc.dk/zsh/";.
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