Question

I would like to have my script accepting variable arguments. How do I check for them individually?

For example

./myscript arg1 arg2 arg3 arg4

 or 

./myscript arg4 arg2 arg3

The arguments can be any number and in any order. I would like to check if arg4 string is present or not irrespective of the argument numbers.

How do I do that?

Thanks,

Answer 1

The safest way — the way that handles all possibilities of whitespace in arguments, and so on — is to write an explicit loop:

arg4_is_an_argument=''
for arg in "$@" ; do
    if [[ "$arg" = 'arg4' ]] ; then
        arg4_is_an_argument=1
    fi
done
if [[ "$arg4_is_an_argument" ]] ; then
    : the argument was present
else
    : the argument was not present
fi

If you’re certain your arguments won’t contain spaces — or at least, if you’re not particularly worried about that case — then you can shorten that to:

if [[ " $* " == *' arg4 '* ]] ; fi
    : the argument was almost certainly present
else
    : the argument was not present
fi