Use portable "command -v" to detect installed programs #765
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The "which" utility is not guaranteed to be installed either, and if it is, its behavior is not portable either. Conversely, the "command -v" shell builtin is required to exist in all POSIX 2008 compliant shells, and is thus guaranteed to work everywhere. Examples of open-source shells likely to be installed as /bin/sh on Linux, which implement the 11-year-old standard: ash, bash, busybox, dash, ksh, mksh and zsh. See: https://mywiki.wooledge.org/BashFAQ/081 https://unix.stackexchange.com/questions/85249/why-not-use-which-what-to-use-then/85250#85250
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Note: I haven't the foggiest clue why this is executing a system() command line in a shell. Does ruby not have a standard library implementation of e.g. python's |
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This will simply think nothing ever exists by default, since "which" doesn't exist, but for extra bonus breakage if you do have a version of |
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UaezapHKqfZ_ACyu6WOU1Q |
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The "which" utility is not guaranteed to be installed either, and if it is, its behavior is not portable either.
Conversely, the "command -v" shell builtin is required to exist in all POSIX 2008 compliant shells, and is thus guaranteed to work everywhere.
Examples of open-source shells likely to be installed as /bin/sh on Linux, which implement the 11-year-old standard: ash, bash, busybox, dash, ksh, mksh and zsh.
See:
https://mywiki.wooledge.org/BashFAQ/081
https://unix.stackexchange.com/questions/85249/why-not-use-which-what-to-use-then/85250#85250