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Re: "here strings" and tmpfiles

From: Greg Wooledge
Subject: Re: "here strings" and tmpfiles
Date: Wed, 20 Mar 2019 08:19:13 -0400
User-agent: NeoMutt/20170113 (1.7.2)

On Wed, Mar 20, 2019 at 07:49:34AM +0700, Robert Elz wrote:
> However, using files for here docs makes here docs unusable in a shell
> running in single user mode with no writable filesystems (whatever is
> mounted is read only, until after file system checks are finished).

Meanwhile, proposals based around /dev/fd/* would also make here docs
unusable in a shell running early in the boot process, before all
file systems are mounted.

Just like that one time L. Walsh tried to write a bash boot script that
used <() to populate an array, and it failed because she was running
it too early in the boot sequence, and /dev/fd/ wasn't available yet.

So, my counterpoints are:

1) Leave it alone.  It's fine.

2) Don't use bash for scripts that run early in the boot sequence.

3) Whatever features you *do* use in boot scripts, make sure they're
   available at the point in the boot sequence when the script runs.

4) Whatever features you use in scripts *in general*, make sure you
   understand how they work.

Even if Chet changed how here docs work in bash 5.1, nobody would
be safe to use those features in their "I'm feeding a password with
a here string" scripts for at least 20 years, because there will
still be people running older versions of bash for at least that long.

Thus, leave it alone.

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