Use [0-9] to match the number
this post was submitted on 08 Jun 2025
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Or, alternatively, [[:digit:]], and dont' forget to add a quntifier + to match multiple digits. See documentaion for details.
awk '/^\/dev\/loop[[:digit:]]+/{print}'
Regex syntax and features vary between implementations. \d isn't supported by BRE/ERE flavors.
GNU grep supports PCRE, so you can use grep -oP '/dev/loop\d' or grep -o '/dev/loop[0-9]' if you are matching only one digit character.
I wish there was one single unifying regex standard.
(obligatory xkcd in 3..2..)
Not sure if I'm understanding, but can't you just pipe the whole thing to awk and capture the first field? Like
echo "/dev/loop0: [2081]:64 (/a/path/to/afile.dat)" | awk -F: '{print $1}'
Which would print
/dev/loop0
That would also print the colon
Edit: missed the separator token. Sorry guys
No, because we're telling to use : as a separator with the -F flag
The field separator is declared to be the colon, with -F:, so the fields end and start at colons.
Why would it print the colon?