Creating a git alias containing bash command substitution and an argument

Question

Got this:

git diff $(git status -s | awk 'FNR == $LINE_NUM {print $2}')

...where line number is the file output by status.

Now I want to create an alias for this command in .gitconfig:

[alias]
diff-num = $WHAT_SHOULD_I_PUT_HERE?

I want this alias to run git's diff command based on the line number argument I'll type in on the command line. I'm new to bash and I'm not sure if I need a bash function to handle this or how to pass the argument into the substituted command.

I think I need an awk.script file to get a variable into the awk command. — StevieD, Mar 30 '19 at 15:18

score 3 · Answer 1 · answered Mar 30 '19 at 17:05

3

The usual form for this is to use the conventional ! shell escape, define an arbitrarily-named shell function and run that, git supplies it with your args. One of my goto's is lgdo,

git config alias.lgdo '!f() { git log --graph --decorate --oneline "${@---all}"; }; f'

also, I have gr and grl as git config --get-regexp {,--local} aliases:

[alias]
        grl = "!f() { git config --local --get-regexp \"${@-.}\"; }; f"
        gr = "!f() { git config --get-regexp \"${@-.}\"; }; f"

answered Mar 30 '19 at 17:05

jthill

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Yeah, I saw that while hunting for an answer to this. I already have the function written in a bash script. There's a nice advantage to be able to see the script on multiple lines so I'm going to stick with it. – StevieD Mar 30 '19 at 17:36

StevieD · Answer 2 · 2019-03-30T18:31:57.383

1

OK, got it worked out. Git alias looks like this:

diff-num = ! diff_num

Bash function is this:

diff_num () {
    line=${1:-1}
    git diff $(git status -s | awk 'FNR == '$line' {print $2}')
}

Function must be exported with the following bash command in your bash config file:

export -f diff_num

edited Mar 30 '19 at 18:31

answered Mar 30 '19 at 16:47

StevieD

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Creating a git alias containing bash command substitution and an argument

2 Answers2