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Re: Crashing the Linux System

X-seq: zsh-workers 51868
From: Bart Schaefer <schaefer@xxxxxxxxxxxxxxxx>
To: LitHack <lithack0@xxxxxxxxx>
Cc: zsh-workers@xxxxxxx
Subject: Re: Crashing the Linux System
Date: Fri, 16 Jun 2023 21:43:02 -0700
Archived-at: <https://zsh.org/workers/51868>
In-reply-to: <CADc_fS3jvV1Go9qWU4g=LSObLqwmC_Pg2ZcxVgSNTkvjxL-eOw@mail.gmail.com>
List-id: <zsh-workers.zsh.org>
References: <CADc_fS3oAhtidGr5bSZ1_26DXPYWkkMy_4O94FKUtMMxRHKYHw@mail.gmail.com> <CADc_fS3jvV1Go9qWU4g=LSObLqwmC_Pg2ZcxVgSNTkvjxL-eOw@mail.gmail.com>

On Fri, Jun 16, 2023 at 8:38 PM LitHack <lithack0@xxxxxxxxx> wrote:
>
> Running the yes command in command substitution will crash the linux shell. According to me inside command the substitution it is creating multiple process(fork).  Command: `yes` or $(yes)

The "yes" command is defined to produce an unending stream of output.
The $(...) substitution is defined to capture all the output from a
command and substitute it as a string.  "All the output" of "yes" is
impossible to capture in finite memory.  The error I get from zsh is
the expected one:
zsh: fatal error: out of heap memory
There definitely are not multiple forks happening.

This is not a bug except in the sense that it was user error to use
$(yes) in the first place.  It's no different than deliberately
writing an infinite loop such as $(while true; do echo y; done).

References:
- Fwd: Crashing the Linux System
  - From: LitHack

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