grep '[:digit:]{1,}-{1,}' *.txt| wc -l This command outputs: 0
grep '1-' *.txt| wc -l However, this command outputs: 10598
Both commands are being run from the same directory. The first command should have returned greater than or equal to the output of the second command. Can anyone shed some insight about what is going on here?
echo 1 | grep '[:digit:]' #nothing.... grep uses a different syntax, you need [[:digit:]] or [0-9].
The {1,} syntax is not supported by basic grep, you can use other modes, like the extended one with -E... Note: Normally one would use + for matching one or more characters....
General note: always test regexes in small parts to see that each part really does what you thought it does. Once the expression gets complicated, it's really hard to tell what went wrong.
[[:digit:]]{1,} without -E, you could use \{1,\}. Or just \+
[0-9]... zillions of different ways.
grep -covergrep | wc -l