Question

why doesn’t this work on a bash command line:

cat `echo "'filename with spaces'"`

It produces these errors:

cat: 'filename: No such file or directory
cat: with: No such file or directory
cat: spaces': No such file or directory

in other words, the single quotes in the string output by the command in the back-ticks is not parsed in the normal way. Does anyone know a way I can make this work? Or perhaps a better approach?

I’ve used cat and echo here as a simple example, but this behavior is rather annoying if, for example, you wish to process a list of files whose names are stored in a file.

Answer 1

Using set -x will be instructive.

What you would need is

cat "$(echo filename with spaces)"

But if what you’re doing is reading newline-delimited file names from a file you should use a while read construct, like this:

while read -r file ; do cat "$file" ; done < file-names.txt

If you don’t want to process each file but instead want to treat them all at once, use

IFS=$'\n' read -d '' -r -a files < file-names.txt
cat "${files[@]}"