Suppose I want to generate a filename based on some given variables.
track=01 title="Some title" album="Some album" echo ${track}. ${title} (${album}) -> 01. Some title (Some album)
Now in the case $album is empty I would get
->01. Some title ()
I would rather want in that case the parenthesis to be removed:
->01. Some title
What I want is something similar to the templates used in foobar like this:
%track%. %title% [(%album%)]
Is it possible to do it in bash (or zsh) but in a single expression like the above and not using if...fi nor nothing like that.
1 Answer
bash: yes, but it's not very pretty:
filename="${track}. ${title}${album:+ ($album)}" The ${var:+value} expands to "value" if $var is both set and non-empty.
Demonstrating:
$ album="Some album" $ filename="${track}. ${title}${album:+ ($album)}" $ declare -p filename declare -- filename="01. Some title (Some album)" $ album="" $ filename="${track}. ${title}${album:+ ($album)}" $ declare -p filename declare -- filename="01. Some title" $ unset album $ filename="${track}. ${title}${album:+ ($album)}" $ declare -p filename declare -- filename="01. Some title" ref: 3.5.3 Shell Parameter Expansion
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