How to invoke bash or shell scripts from a haskell program?

Question

I'm writing some shell scripts with haskell, which I'm running in gitbash, but there are a few other existing scripts I'd like to be able to use from those scripts.

For example, I'd like to run maven goals or do a git pull, but without having to integrate specifically with those tools.

Is there a way to do this?

yes, and asynchronously https://github.com/friedbrice/dotfiles/blob/master/bin/git-fetch.hs :-) — Fried Brice, Aug 31 '18 at 19:02
Does this answer your question? [Executing a system command in Haskell](https://stackoverflow.com/questions/3470955/executing-a-system-command-in-haskell) — Chris Stryczynski, Apr 05 '20 at 13:28

score 30 · Accepted Answer · edited Nov 12 '16 at 13:04

30

You can use System.Process. For example, executing seq 1 10 shell command:

> import System.Process

> readProcess "seq" ["1", "10"] ""
"1\n2\n3\n4\n5\n6\n7\n8\n9\n10\n"
it :: String

> readProcessWithExitCode  "seq" ["1", "10"] ""
(ExitSuccess,"1\n2\n3\n4\n5\n6\n7\n8\n9\n10\n","")
it :: (GHC.IO.Exception.ExitCode, String, String)

edited Nov 12 '16 at 13:04

somesoaccount

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answered May 10 '12 at 14:54

ДМИТРИЙ МАЛИКОВ

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score 11 · Answer 2 · answered May 10 '12 at 14:58

Yes, it is possible. You can use process package, which exports many useful functions. Simplest one is System.Cmd.system, which can run some application in shell, yielding exit code.

More advanced features are provided too in the System.Process module. With this module you can run process and communicate with it in many ways (input piping, exit codes, waiting for process to stop, modify its environment etc).

score 7 · Answer 3 · edited Apr 30 '15 at 21:39

7

Of course. You can start by using system to invoke external processes.

More sophisticated piping and process control is available in a cross-platform way from the System.Process library.

Finally, you can consider porting your shell scripts to Haskell, via shell DSLs.

edited Apr 30 '15 at 21:39

cic

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answered May 10 '12 at 14:55

Don Stewart

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score 7 · Answer 4 · edited Feb 07 '17 at 19:29

7

Turtle is pretty nice modern haskell library for this.

edited Feb 07 '17 at 19:29

Elliot Cameron

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answered Apr 30 '15 at 23:03

jhickner

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How to invoke bash or shell scripts from a haskell program?

4 Answers4

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