Question

My bash script gets filenames with spaces and other odd characters.

How do I print these filenames back out to the terminal with the escapes in the right places so the user can just copy-and-repaste the filename so that it can be reused as a parameter to the same or another script?

I wrote a test script which reads as follows:

    #! /bin/bash

    echo ""
    echo "testing the insertion of '\' in filenames having spaces"
    echo "the parameter you gave was: '$1'"
    echo "when printed directly the filename looks like: '$1'"
    echo "when printed with echo \$(printf '%q' $x) it looks like: " $(printf '%q' $1)

Running the script went as follows:

    bash test.sh this\ filename\ has\ spaces
    testing the insertion of '\' in filenames having spaces

    the parameter you gave was: 'this filename has spaces'
    when printed directly the filename looks like: 'this filename has spaces'
    when printed with echo $(printf '%q' ) it looks like:  thisfilenamehasspaces

What I want to see the script produce is:

    when printed directly the filename looks like: 'this\ filename\ has\ spaces'

Seems simple but the question is hard to form for Google. All help appreciated. Thanks.

Answer 1

This:

printf '%q' $1

means this:

printf '%q' this filename has spaces

which, since printf '%q' concatenates its arguments, means this:

printf '%q' thisfilenamehasspaces

What you want is this:

printf '%q' "$1"

which tells printf '%q' that this filename has spaces is all one argument, so it will quote the spaces inside.

I’d also recommend putting the command-substitution inside double-quotes:

echo "when printed with echo \$(printf '%q' $x) it looks like: $(printf '%q' "$1")"

which happens not to be necessary in this case, but will be necessary if the filename ever has a character that causes printf '%q' to use $'...'-style quoting instead of backslashes.