Prompt/Ask/Question "Prompt text [y/n]" for POSIX sh. Different exit code for (cant read stdin) and (wrond input typed)
note: Instead of options this script uses complex matching
to first argument $1 of (upper Y|N or lower case y|n) and (1 y|n|'' letter or full yes|no|maybe).
See YN_confirm help message below
$ if YN_confirm y 'My question?'
then echo ok
else exit code: $?
fi
My question? [Y/n]
(( when user accepts by typing: "yes"|"yNO"|Ynot|[Yy]* )): ok
(( when user rejects by typing: "no"|"nYES"|"Nu"|[Nn]* )): exit code: 3
(( when user stypes not valid input: "idk" )): exit code: 3
(( when cant reed input )): exit code: 5
$ if YN_confirm Yes 'Do you want to clear cache?'
then echo will delete something un-needed from ~/.cache/...
else echo exit code $?
fi
Do you want to clear cache? [Y/n]
(( when user types: "idk"|"" )): will delete something un-needed from ~/.cache/...
(( when can't read input )): will delete something un-needed from ~/.cache/...
(( and only when user types: "n"|[Nn]* )): exit code: 1
$ if YN_confirm n 'Do you want to delete something? you may need it'
then echo will delete something
else echo exit code $?
fi
Do you want to delete something? you may need it [y/N]
(( when user types: ""|"no"|[Nn]* )): exit code: 1
(( when user types: "idk" )): exit code: 3
(( when can't read input )): exit code: 5
(( only when user types: "yes"|[Yy]* )): will delete somethingnote: exit code 4 is for error in arguments
$ YN_confirm --help
Usage: YN_confirm [-x|+x] [--stdin|-S] [--print-response] [default] [...prompt text]
Options:
--help display this help message
--help-long display long help message with argument examples
--stdin|-S read response from standard input
--print-response print response after succsesful read
-x|+x debug, turn on/off xtrace on shell
Arguments:
[...prompt text] is joined by $IFS (most likely a space)
[default]:
I. The length of [default] argument matters
when `read` command failed
(1 char)|'' => exit code 5
(2+ chars) => exit code 0
II. The capitalization of [default] argument matters
when input is not as expected
(UPPER) => exit code 0
(lower)|'' => exit code 3
$ YN_confirm --help-long
Usage: YN_confirm [-x|+x] [--stdin|-S] [--print-response] [default] [...prompt text]
Options:
--help display help message
--help-long display this long help message with argument examples
--stdin|-S read response from standard input
--print-response print response after succsesful read
-x|+x debug, turn on/off xtrace on shell
Arguments:
[...prompt text] is joined by $IFS (most likely a space)
[default]:
I. The length of [default] argument matters
when `read` command failed
(1 char)|'' => exit code 5
(2+ chars) => exit code 0
1. when `read` failed and [default] in [Yy]es => exit code 0
2. when `read` failed and [default] in [Nn]o => exit code 0
3. when `read` failed and [default] in [Mm]aybe => exit code 0
4. when `read` failed and [default] in '' => exit code 5
5. when `read` failed and [default] in [Yy] => exit code 5
6. when `read` failed and [default] in [Nn] => exit code 5
II. The capitalization of [default] argument matters
when input is not as expected
(UPPER) => exit code 0
(lower)|'' => exit code 3
1. when $response not in [YyNn]*|'' and [default] in Y|Yes => exit code 0
2. when $response not in [YyNn]*|'' and [default] in N|No => exit code 0
3. when $response not in [YyNn]*|'' and [default] in Maybe => exit code 0
4. when $response not in [YyNn]*|'' and [default] in ''|maybe => exit code 3
5. when $response not in [YyNn]*|'' and [default] in y|yes => exit code 3
6. when $response not in [YyNn]*|'' and [default] in n|no => exit code 3
III. [y/n/''] matters, Examples for empty input:
1. when \response in '' and [default] in [Yy]|[Yy]es => exit code 0
2. when \response in '' and [default] in [Nn]|[Nn]o => exit code 1
4. when \response in '' and [default] in ''|[Mm]aybe => exit code 2
Exit status:
0 => answer is Yes
1 => answer is No
2 => no answer and no default answer specified
3 => not expected answer
4 => bad command arguments
5+ => not expected `read` fail