Make a Bash Alias That Takes a Parameter?
I Used to Use Cshell (Csh), Which Lets You Make an Alias That Takes a Parameter. the Notation Was Something Like Alias Junk="Mv \\! * ~/. Trash" in Bash, This...
I used to use CShell (csh), which lets you make an alias that takes a parameter. The notation was something like
alias junk="mv \\!* ~/.Trash"
In Bash, this does not seem to work. Given that Bash has a multitude of useful features, I would assume that this one has been implemented but I am wondering how.
24 Answers
Bash alias does not directly accept parameters. You will have to create a function.
alias does not accept parameters but a function can be called just like an alias. For example:
myfunction() {
#do things with parameters like $1 such as
mv "$1" "$1.bak"
cp "$2" "$1"
}
myfunction old.conf new.conf #calls `myfunction`
By the way, Bash functions defined in your .bashrc and other files are available as commands within your shell. So for instance you can call the earlier function like this
$ myfunction original.conf my.conf
Refining the answer above, you can get 1-line syntax like you can for aliases, which is more convenient for ad-hoc definitions in a shell or .bashrc files:
bash$ myfunction() { mv "$1" "$1.bak" && cp -i "$2" "$1"; }
bash$ myfunction original.conf my.conf
Don't forget the semi-colon before the closing right-bracket. Similarly, for the actual question:
csh% alias junk="mv \\!* ~/.Trash"
bash$ junk() { mv "$@" ~/.Trash/; }
Or:
bash$ junk() { for item in "$@" ; do echo "Trashing: $item" ; mv "$item" ~/.Trash/; done; }
The question is simply asked wrong. You don't make an alias that takes parameters because alias just adds a second name for something that already exists. The functionality the OP wants is the function command to create a new function. You do not need to alias the function as the function already has a name.
I think you want something like this :
function trash() { mv "$@" ~/.Trash; }
That's it! You can use parameters $1, $2, $3, etc, or just stuff them all with $@
TL;DR: Do this instead
Its far easier and more readable to use a function than an alias to put arguments in the middle of a command.
$ wrap_args() { echo "before $@ after"; }
$ wrap_args 1 2 3
before 1 2 3 after
If you read on, you'll learn things that you don't need to know about shell argument processing. Knowledge is dangerous. Just get the outcome you want, before the dark side forever controls your destiny.
Elena Rostova holds a Master's degree in Public Health Journalism. She covers groundbreaking medical research, holistic wellness trends, mental health awareness, and nutritional science.
