Bad Advice on Replacing "which" with "command -v" - Not Equivalent

[AdamDanischewski]

For bugs

• Rule Id: SC2230

• My shellcheck version (shellcheck --version or "online"): version: 0.5.0

• [X ] The rule's wiki page does not already cover this (e.g. https://shellcheck.net/wiki/SC2086)

• [ X] I tried on shellcheck.net and verified that this is still a problem on the latest commit

Here's a snippet or screenshot that shows the problem:

Here's what shellcheck currently says:

SEQ_CMD="$(which seq)"||MISSING_CMDS+=("seq");declare -r SEQ_CMD
^-- SC2230: which is non-standard. Use builtin 'command -v' instead.

Here's what I wanted or expected to see:

Using command -v vs which is probably bad advice. For instance if an alias exists for a command and you issue a "which command" you will get the full path to the first version in the PATH variable found. If you issue a command -v you will get the alias if one exists. These two commands are not interchangeable.

Try:
$> alias cp='_(){ ((${#}==1)) && cp -nv "${1}" "$(pwd)" || cp -nv "${1}" "${2}";};_'
now, you can see the difference:
$> which cp
/bin/cp
$> command -v cp
alias cp='(){ ((${#}==1)) && cp -nv "${1}" "$(pwd)" || cp -nv "${1}" "${2}";};'

When you are using which to set help set command path variables you don't want it loaded with alias declarations.

[AdamDanischewski]

I guess that was a bad example for files. Instead, try sourcing an alias functions file from another script:

s.bsh:
function cp() { echo hi; }

r.bsh:

#!/bin/bash 
. s.bsh 
which cp
command -v cp

and run:

$> ./r.bsh 
/bin/cp
cp

Here you can see that command -v prints simply the name of the function and which produces the fully qualified path.

[awgeorge]

It also incorrectly suggests to use command -v when using the -a parameter of which

$(which -a open)
  ^---^ SC2230: which is non-standard. Use builtin 'command -v' instead.

[awgeorge]

See also: #1162

[AdamDanischewski]

@awgeorge Thanks for the update. I'll close this duplicate - and yes, command -v is not a subsitute for which -a.

[AdamDanischewski]

Duplicate of #1162.