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Zaira avatar Ubuntu

Bash Function/Alias name collision causes seg fault

me flag
Zaira

The problem in this post also happened to me. mkdir crashes bash

I couldn't comment there because no reputation. Can anyone elucidate why this happens? It happens at runtime Not when the function is loaded. Here is the paste of the identical issue.

md() 
{  
    [ $# -eq 0 ] && { echo "$0 dirname [permissions]"; return; }
    [ -d "$1" ] && { echo "%1 already exists!"; return; }
    mkdir -m ${2:-0755} -p "$1"
}

"Problem was that I had previously had an alias like alias md="mkdir" so when bash parsed the new bash function, it expanded the md() to mkdir() and the function became infinitely recursive and crashed the shell. "

I felt this issue was aptly found but i do not understand the reasoning. I don't understand any possible reason the alias expansion is misdirecting the fully qualified shell function. Backwards right?

Sorry for the dupe, please read why before a callout.

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steeldriver
Aliases are really just text replacement macros - so when you try to *define* `md() { ... }` after defining `md=mkdir` you actually end up with `mkdir() { ... }`. Try printing out the function defs with `declare -p -f md` and `declare -p -f mkdir` to see what I mean.
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Zaira avatar Ubuntu
me flag
Zaira

"Aliases are really just text replacement macros - so when you try to define md() { ... } after defining md=mkdir you actually end up with mkdir() { ... }. Try printing out the function defs with declare -p -f md and declare -p -f mkdir to see what I mean." – steeldriver

zi@zi-top:~$ declare -p -f nd
bash: declare: nd: not found
zi@zi-top:~$ declare -p -f mkdir
mkdir () 
{ 
    mkdir -p "$@"
}
zi@zi-top:~$ nd () {
        mkdir -p "$@"
}
zi@zi-top:~$ declare -p -f nd
bash: declare: nd: not found

I see that what steeldriver said is true, i think it`s a strange architectural decision with prob some kind of reasoning in the code is text bashism wurl. Thanks!

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