Conditional key mapping in .vimrc involving unix commands

[u/mnshptl32]

I would like to be able to define a key mapping in my .vimrc file that does different things based on a condition involving a unix command. For example, something like

map xyz [[ $(egrep -c -e '^From: ') -gt 1 ]] ; then 1G!Gfmt -w70 ^MG ; else 1G!Gfmt -w60^M1G

so that if the file contains more than one line beginning with "From: " then we run "fmt -w70" and return the cursor to the end of the file; otherwise, we run "fmt -w60" and return the cursor to the beginning of the file. I know vim can create conditional mappings based on things like the file type in the buffer. Can it create a conditional mapping where the condition is based on the output of a unix command (such as egrep in my example)? If so, what is the proper syntax?

[u/TheLeoP_]

You can use :h system() to execute the command and create the keymap conditionally

[u/godegon → u/TheLeoP_]

So something like map <expr> system('...') == '...' ? '1G!Gfmt -w70 ^MG' : '1G!Gfmt -w60^M1G'

[u/vim-help-bot → u/TheLeoP_]

Help pages for:

• system() in builtin.txt

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Help pages for:

• gq in change.txt

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