simple-cmd

Simple String-based process commands

https://github.com/juhp/simple-cmd

LTS Haskell 24.51:0.2.8
Stackage Nightly 2026-07-20:0.2.8
Latest on Hackage:0.2.8

See all snapshots simple-cmd appears in

BSD-3-Clause licensed and maintained by Jens Petersen
This version can be pinned in stack with:simple-cmd-0.2.8@sha256:88e5e7ae3cc2b04dc6328102a110b996232184bb4a2b19b2a5c1fa2415bd0415,2599

Module documentation for 0.2.8

Hackage Stackage LTS Stackage Nightly

simple-cmd

Some simple String wrappers of readProcess, readProcessWithExitCode, rawSystem from the Haskell process library.

Usage

import SimpleCmd

cmd_ :: String -> [String] -> IO ()

outputs to stdout. For example

cmd_ "echo" ["Hello"]
cmd_ "git" ["clone", url]

This can shortened to git_ "clone" [url].

cmd :: String -> [String] -> IO String

returns stdout as a String. eg

date <- cmd "date" []

There are also cmdBool, cmdMaybe, cmdList, shell, and others.

Simple pipes are also supported:

pipe_ ("echo",["hello"]) ("grep",["ello"])

pipeBool returns True if both commands succeed.

Other examples:

gitBranch :: IO String
grep_ pat file :: IO Bool
sudo_ c args :: IO ()
timeIO :: IO a -> IO a

See the library documentation for more details.

Changes

Version history for simple-cmd

0.2.8 (2026-07-18)

  • +-+: use lastMay and headMay
  • removeTrailingNewline: use safe lastMay
  • add timeIOHelper
  • cmdLog_: use quoteCmd
  • cmdN: only quote arg if it contains space(s)

0.2.7 (2022-06-20)

  • allow building on Windows without unix (no sudo*)
  • add ‘newline’ to output newline
  • rename ‘sudo_’ to ‘sudoLog’ (‘sudo_’ no longer outputs log)
  • export ‘sudoInternal’ helper
  • provide ‘cmdLog_’ to be used instead of ‘cmdLog’

0.2.6 (2022-05-18)

  • timeIO: print the duration in hours and minutes, not just seconds

0.2.5 (2022-04-24)

  • cmdN: quote arguments with show
  • add timeIO: runs action and prints the time it took

0.2.4 (2022-03-27)

  • error’ and warning are now strict
  • pipeBool: return False if either end fails
  • add filesWithExtension and fileWithExtension
  • initial basic testsuite

0.2.3 (2020-12-20)

  • most commands now use removeTrailingNewline
  • cmdFull: wrapper of readProcessWithExitCode
  • cmdStderrToStdoutIn: like cmdStderrToStdout but reads a String
  • pipe3 connects 3 commands

0.2.2 (2020-06-17)

  • grep: no longer errors for no match
  • add cmdStderrToStdout: redirects stderr to stdout
  • add gitBool
  • define gitBranch using “git rev-parse” (internal change)
  • now export ifM and whenM from extra

0.2.1 (2019-12-12)

  • add cmdTry_: only runs if available
  • add ifM and whenM
  • add needProgram

0.2.0 (2019-06-03)

  • add warning command
  • API change: sudo and sudo_
  • add shellBool
  • add pipe, pipe_, pipeBool, pipeFile_, pipe3
  • quoteCmd uses showCommandForUser

0.1.4 (2019-04-08)

  • export error’
  • add cmdLog (deprecates cmdlog)

0.1.3.1 (2019-03-15)

  • sudo: ignored for root or when no sudo installed

0.1.3 – 2019-02-20

  • gitDiffQuiet
  • fix rwGitDir regexp
  • use errorWithoutStackTrace

0.1.2 – 2018-10-28

  • grep
  • improve haddock documentation

0.1.1 – 2018-10-02

  • cmdLines
  • Git: grepGitConfig
  • new Rpm: rpmspec

0.1.0.0 – 2018-09-13

  • Initial release, providing: cmd, cmd_, cmdBool, cmdMaybe, cmdStdIn, cmdlog, cmdN, cmdIgnoreErr, cmdQuiet, cmdSilent, cmdStdErr, egrep_, grep_, logMsg, removePrefix, removeStrictPrefix, removeSuffix, shell, shell_, sudo, (+-+)
  • A few git commands

Local Variables:

mode: text

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