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---
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short-description: Running external commands
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...
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# External commands
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As a part of the software configuration, you may want to get extra
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data by running external commands. The basic syntax is the following.
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```meson
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r = run_command('command', 'arg1', 'arg2', 'arg3')
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if r.returncode() != 0
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# it failed
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endif
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output = r.stdout().strip()
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errortxt = r.stderr().strip()
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```
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Additionally, since 0.50.0, you can pass the command [`environment`](Reference-manual.html#environment-object) object:
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```meson
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env = environment()
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env.set('FOO', 'bar')
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run_command('command', 'arg1', 'arg2', env: env)
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```
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The `run_command` function returns an object that can be queried for
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return value and text written to stdout and stderr. The `strip` method
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call is used to strip trailing and leading whitespace from
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strings. Usually output from command line programs ends in a newline,
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which is unwanted in string variables. The first argument can be
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either a string or an executable you have detected earlier with
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`find_program`.
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Note that you can not pass your command line as a single string. That
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is, calling `run_command('do_something foo bar')` will not work. You
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must either split up the string into separate arguments or pass the
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split command as an array. It should also be noted that Meson will not
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pass the command to the shell, so any command lines that try to use
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things such as environment variables, backticks or pipelines will not
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work. If you require shell semantics, write your command into a script
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file and call that with `run_command`.
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