Add prefix and suffix to $@ in bash

Question

How to add suffix and prefix to $@?

If I do $PREFIX/$@/$SUFFIX, I get the prefix and the suffix only in the first parameter.

Answer 1

I would use shell [ parameter expansion ] for this

$ set -- one two three
$ echo "$@"
one two three
$ set -- "${@/#/pre}" && set -- "${@/%/post}"
$ echo "$@"
preonepost pretwopost prethreepost

Notes

• The # matches the beginning
• The % matches the end
• Using double quotes around ${@} considers each element as a separate word. so replacement happens for every positional parameter

Answer 2

Let's create a parameters for test purposes:

$ set -- one two three
$ echo "$@"
one two three

Now, let's use bash to add prefixes and suffixes:

$ IFS=$'\n' a=($(printf "pre/%s/post\n" "$@"))
$ set -- "${a[@]}"
$ echo -- "$@"
pre/one/post pre/two/post pre/three/post

Limitations: (a) since this uses newline-separated strings, it won't work if your $@ contains newlines itself. In that case, there may be another choice for IFS that would suffice. (b) This is subject to globbing. If either of these is an issue, see the more general solution below.

On the other hand, if the positional parameters do not contain whitespace, then no change to IFS is needed.

Also, if IFS is changed, then one may want to save IFS beforehand and restore afterward.

More general solution

If we don't want to make any assumptions about whitespace, we can modify "$@" with a loop:

$ a=(); for p in "$@"; do a+=("pre/$p/post"); done
$ set -- "${a[@]}"
$ echo "$@"
pre/one/post pre/two/post pre/three/post