CODEWITHSUNDEEP
bashshellunixzsh
Steven Lu
Steven Lu

Reputation: 43427

Converting a history command into a shell script

This is sort of one of those things that I figured a lot of people would use a lot, but I can't seem to find any people who have written about this sort of thing.

I find that a lot of times I do a lot of iteration on a command-line one-liner and when I end up using it a lot, or anticipate wanting to use it in the future, or when it becomes cumbersome to work with in one line, it generally is a good idea to turn the one-liner into a shell script and stick it somewhere reasonable and easily accessible like ~/bin.

It's obviously too cumbersome to use any sort of roundabout method involving a text editor to get this done, and it's possible to simply do it on the shell, for instance in zsh typing 

echo "#!/usr/bin/env sh" > ~/bin/command_from_history_number_523.sh && echo !523 >> ~/bin/command_from_history_number_523.sh

followed by pressing Tab to inject the !523rd command and somehow shoehorning it into an acceptable string to be saved.

This is particularly cumbersome and has at minimum three problems:

So it looks like I need to do some meta shell scripting here.

I think a good solution would function under both bash and zsh, and it should probably work by taking two arguments, an integer for the history command number and a name for the shell script to poop out in a hardcoded directory which contains that one command. Furthermore, under bash, it appears that multi-line commands are treated as separate commands, but I'm willing to assume that we only care about one-liners here and I only use zsh anyway at this point.

The stumbling block here is that i think I'll still be running shell scripts through bash even when using zsh, so it won't likely then be able to parse zsh's history files. I may need to make this into two separate programs then.

Update: I agree with @Floris 's comment that direct use of the commands like !! would be helpful though I am not sure how to make this work. Suppose I have the usage be 

mkscript command_number_24 !24

this is inadequate because mkscript will be receiving the expanded out contents of the 24th command. if the 24th command contains any file globs or somesuch they will have been expanded already. This is bad, and I basically want the contents of the history file, i.e. the raw command string. I guess this can be worked around by manually implementing those shortcuts in here. Or just screw it and just take an integer argument.

Upvotes: 2

Views: 1898

Answers (1)

Brian Campbell
Brian Campbell

Reputation: 332816

function mkscript() { 
    echo '#!/bin/bash' > ~/bin/$2
    history -p '!'$1 >> ~/bin/$2
}

Only tested in Bash.

Update from OP: In zsh I can accomplish this with fc -l $2 $2

Upvotes: 3

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