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I've got sympathies with both sides of this argument. Bashisms are powerful, flexible, and occasionally performant. They're also non-portable, and you're apt

I've got sympathies with both sides of this argument. Bashisms are powerful, flexible, and occasionally performant. They're also non-portable, and you're apt to discover this whilst in an emergency situation with limited resources, most of all time. Having to edit shell scripts into POSIX conformance on a smartphone SSH session is No Bueno. There are an awful lot of systems which have either no, or old, Bash. Most prevalent of the latter is MacOS / OSX, which is now nagging me on each shell initialisation that the current supported standard is not bash but zsh. Scripts linked to /bin/bash will of course run, but the last update was version 3.2.57(1) if my system reports correctly. The most recent GNU Bash release is 5.3 according to <https://ftp.gnu.org/gnu/bash/ https://ftp.gnu.org/gnu/bash/>. And that's hardly the only old Bash floating around. On many systems, including many routers, DSL/cable modems, and other embedded devices, shell is some alternate variant (dash is /bin/sh on Debian, ash on RHEL's initrd IIRC, which last I fought with it was a script-only interpreter, not capable of running interactive commands, fucking annoying as hell). And there are still legacy Unix systems running Bourne, ksh, or other shells. Not to mention the phenomenal number of systems for which busybox provides much if not all of the userland environment, including /bin/sh. And is not bashism-capable. Ignoring POSIX works fantastically until it doesn't. Caveat scriptor.

chasil 2y ago
If you want the most powerful shell, ksh93 has the most features without doubt. Since David Korn retired, it has been adrift with few updates. The dash shell can be compiled with libedit to implement "set -o vi" (which is also POSIX), and is pleasant to use this way.
imtringued 2y ago
I don't know why someone would subject themselves to bash if the common argument in favour of it is a lie. People say that bash is already installed on the system. Then people like you point out that it isn't.
- dredmorbius 2y ago
  Bash is installed on my own primary system(s). And generally a quite recent version. When I'm coding my own utility scripts (or more likely: writing one-liners which may get reused through shell history, possibly eventually being memorialised as scripts), I'll make heavy use of bashisms for the reasons I've noted elsewhere: powerful, convenient, often performant. But if I'm inflicting those or other scripts on other systems I'm highly cognisant that not all systems have either a modern bash, or bash at all, and will either write POSIX-conformant scripts there, or remove bashisms from my own scripts. That is, availing myself to benefits whilst recognising limits to my approach. A key benefit of scripting in the shell language used most frequently is that one is highly familiar with it. Scripting-only languages tend to be less familiar. They're also less available (sed and awk being the principle exceptions, which are also mandated under POSIX, and for which GNU variants also have idiosyncrasies (I run into this on MacOS all the time, and tend to make use of GNU sed/awk there). Perl, Ruby, Python, Lua, node.js, Tcl, etc., have more capabilities, but are also unavailable on a large number of systems. (Often old or small systems. to be sure, but numerous all the same.)

chasil 2y ago

If you want the most powerful shell, ksh93 has the most features without doubt. Since David Korn retired, it has been adrift with few updates. The dash shell can be compiled with libedit to implement "set -o vi" (which is also POSIX), and is pleasant to use this way.

imtringued 2y ago

I don't know why someone would subject themselves to bash if the common argument in favour of it is a lie. People say that bash is already installed on the system. Then people like you point out that it isn't.

dredmorbius 2y ago
Bash is installed on my own primary system(s). And generally a quite recent version. When I'm coding my own utility scripts (or more likely: writing one-liners which may get reused through shell history, possibly eventually being memorialised as scripts), I'll make heavy use of bashisms for the reasons I've noted elsewhere: powerful, convenient, often performant. But if I'm inflicting those or other scripts on other systems I'm highly cognisant that not all systems have either a modern bash, or bash at all, and will either write POSIX-conformant scripts there, or remove bashisms from my own scripts. That is, availing myself to benefits whilst recognising limits to my approach. A key benefit of scripting in the shell language used most frequently is that one is highly familiar with it. Scripting-only languages tend to be less familiar. They're also less available (sed and awk being the principle exceptions, which are also mandated under POSIX, and for which GNU variants also have idiosyncrasies (I run into this on MacOS all the time, and tend to make use of GNU sed/awk there). Perl, Ruby, Python, Lua, node.js, Tcl, etc., have more capabilities, but are also unavailable on a large number of systems. (Often old or small systems. to be sure, but numerous all the same.)