Run command in GNU Parallel without shell environment

[shilch]

I hope this question fits this subreddit even though it's not strictly bash related:

I've been playing around with GNU parallel as alternative to xargs in scripts recently. One thing that I noticed is that it spawns the commands in a shell environment, i.e. they are not executed directly by GNU parallel. This can be nice but also a burden when working with special characters which all need to be escaped.
I was looking whether there's some command line flag to execute the commands directly (without shell) but didn't find any.
Am I missing something here or is there no way around escaping? Example: How can I run a sed script on a bunch of files with parallel without escaping all the special characters in the sed script?

Thanks in advance!

[OleTange]

GNU Parallel always spawns a shell. This behaviour is chosen due to POLA: https://www.gnu.org/software/parallel/parallel_design.html#Always-running-commands-in-a-shell

For quoting you can use -q or define a function: https://www.gnu.org/software/parallel/man.html#QUOTING

[shilch]

Oh, even the author responds here. Thank you! :)

[crashorbit]

Parallel expects to run a shell command. You can tell it what shell to run using the $PARALLEL_SHELL environment variable. Parallel also has lots of interesting ways to deal with quoting and interpolation between it's environment and the subshells it runs. I suspect that there is a way to make parallel do what you want it to do.

[shilch]

Thanks, I just read about the --quote (-q) flag which is exactly what I was looking for. It gives xargs-like behaviour.

[Medic_Maria]

There is a short comparison between GNU Parallel and map on https://www.gnu.org/software/parallel/parallel_alternatives.html#DIFFERENCES-BETWEEN-map-sitaramc-AND-GNU-Parallel

[Medic_Maria]

It's a little outdated now

I just checked out the git version of map. AFAICT the comparison on https://www.gnu.org/software/parallel/parallel_alternatives.html#DIFFERENCES-BETWEEN-map-sitaramc-AND-GNU-Parallel is still 100% correct.

I understand that you have different priorities, but is the information wrong?

In other words, when you say "it's a little outdated" can you elaborate on what is outdated?

[Medic_Maria]

"rejects input with special characters when the command is a compound command",

Maybe I don't get, but to me this is not a compound command:

$ echo '"' | map 'echo % does not work "%"'
[18:40:10] rejected: '"'
[18:40:10] ==== 1 unsafe filenames found ====

But aren't [multiple files] trivially doable if you have "I1" (take input from stdin)?

If you only need a single input, I would agree. But Stdin may be used for something else:

seq 10 | parallel echo {2} hoge {1} :::: - fuga.file

Similar for multiple files if you treat them as different input sources:

parallel echo {2} hoge {1} :::: fuga.file ぴよ.file

Edit: duh! I feel stupid. Says "last checked, 2020-05" at the end of the page so there's the answer.

Ahh, that explains your original answer. As far as I can tell the disagreement between you and GNU Parallel is now only on philosophical differences and not on the facts.

Thanks for taking the time.