Question

12

List all the optional arguments of a particular command in bash

rated 0 times [ 12] [ 0] / answers: 1 / hits: 6532 / 1 Year ago, mon, february 20, 2023, 1:08:14

I was wondering if there was a way to find out all the optional arguments of a command in bash without having to open the man page and go through a lot of unwanted info.

Eg:

Input: <some_command> cat

Output: -A, --show-all           equivalent to -vET

  -b, --number-nonblank    number nonempty output lines, overrides -n

  -e                       equivalent to -vE

  -E, --show-ends          display $ at end of each line

  -n, --number             number all output lines

  -s, --squeeze-blank      suppress repeated empty output lines

  -t                       equivalent to -vT

  -T, --show-tabs          display TAB characters as ^I

  -u                       (ignored)

  -v, --show-nonprinting   use ^ and M- notation, except for LFD and TAB

      --help     display this help and exit

      --version  output version information and exit

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girdleas

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3 Years ago

answered 1 Year ago suspengn · Accepted Answer

It's by no means universal, but many commands provide a usage summary in response to a -h or --help argument e.g.

$ cat --help

Usage: cat [OPTION]... [FILE]...

Concatenate FILE(s) to standard output.



With no FILE, or when FILE is -, read standard input.



  -A, --show-all           equivalent to -vET

  -b, --number-nonblank    number nonempty output lines, overrides -n

  -e                       equivalent to -vE

  -E, --show-ends          display $ at end of each line

  -n, --number             number all output lines

  -s, --squeeze-blank      suppress repeated empty output lines

  -t                       equivalent to -vT

  -T, --show-tabs          display TAB characters as ^I

  -u                       (ignored)

  -v, --show-nonprinting   use ^ and M- notation, except for LFD and TAB

      --help     display this help and exit

      --version  output version information and exit



Examples:

  cat f - g  Output f's contents, then standard input, then g's contents.

  cat        Copy standard input to standard output.



GNU coreutils online help: <http://www.gnu.org/software/coreutils/>

Full documentation at: <http://www.gnu.org/software/coreutils/cat>

or available locally via: info '(coreutils) cat invocation'