bash函数与别名冲突

Question

How could I detect aliases before define same name function in bash script file(this file will be sourced in another script)?

Something like meta-programming in bash (define another name function if this name is already taken by aliases?)

$ source t.sh
$ alert 'test'
test
$ type alert
alert is a function
alert () 
{ 
    echo -n "$@"
}

$ alias alert='notify-send --urgency=low -i error'
$ source t.sh
bash: t.sh: line 1: syntax error near unexpected token `('
bash: t.sh: line 1: `alert() { echo "$@"; }'
$ type alert
alert is aliased to `notify-send --urgency=low -i error'

$ cat t.sh
alert() { echo "$@"; }

Answer 1

You don't need to. Aliases by default are not expanded in non-interactive shells.

Answer 2

if alias alert 2> /dev/null; then
    echo "'alert' already an alias"
else
    source t.sh
fi

The alias command exists with non-zero status if its single argument is not an alias.

Answer 3

Well, which <name> returns 0 if name is an alias.

So to check if custom_name is already used you can do:

if [ $(which custom_name >/dev/null; echo $?) -eq 0 ]
then
    echo "Already aliased"
    return 1
else
    echo "Free to use"
    return 0
fi

---

Note: This will not check if there is a bash function called custom_name in the current shell.