I have a bash function (slightly simplified for explaining)
copy_to() {
cp $1 $2 $3
}
This works fine:
copy_to -f /demo/example1.xml new_demo/
But Let's say I want to copy all the xml files, the following code will have issues:
copy_to -f /demo/*.xml new_demo/
Obviously I could just write cp -f /demo/*.xml new_demo/, but is there anyway to get the copy_to function to work for a list of files (which passes more than just 3 parameters) as well as a single file?
There are $@ and $* which contain a list of all parameters. You should use $@, because it works inside of double quotes. Else, file names containing spaces would break your code.
copy_to() {
cp "$@"
}
If one of the parameters is special, you can use the shift command to remove it from the list of parameters, like so:
example() {
destination="$1"
shift
echo "copying $@ to $destination"
}
shift removes the first parameter from the list, therefore you’ll have to save it in another location first. After calling shift, the contents of $1 will be what was $2, $2 will contain what was $3 and so on. $@ expands to all parameters (excluding those that were removed by shift).
Note that you cannot shift parameters off the end of your parameter list, only from the beginning.
${@:0:$((${#@} - 1))} (subtract 2 to omit the last two, etc.). Writing for a single shell only is not always bad - why have other shells if all you're going to use is the POSIX (or original Bourne) subset?${@:1:$#-1}If you need to iterate over the arguments:
f() {
for arg
do
do_something $arg
done
}
The in $@ is implied in for arg (explicitly: for arg in $@).
As Scytale said $@ and $* contain a list of all parameters. $# contains param count.
You can consider use getopts command for parameter parsing.
Best regards
