Buongiorno,
I am trying to grep all the patterns that look like: [00 0] or [ 0000] but not [00] or [0000] : there has to be at least one space.
Naively, I thought that
grep -P '\[.* .*\]'
would do it ; when I copy paste the regex in regex101 with some test cases, I get the following:
unmatched:
0 0
000
[00]
[0]
[00]
matched:
[0 0]
[ 0]
[0 ]
[ 0 ]
[ 0 ]
which is exactly what I want.
But grep seems to match also the things between brackets but with no space:
[00]
[0]
[00]
What am I missing ?
\[0* 0*\]
seems to work but I'm going to have cases where it's not only 0...
CodePudding user response：
This grep would work with BRE (basic regex), it doesn't require ERE (extended regex) or experimental -P (perl regex):
grep '\[[^] ]* [^]]*]' file
[0 0]
[ 0]
[0 ]
[ 0 ]
[ 0 ]
If you have only zeroes and spaces inside the [...] then try:
grep '\[0* [0 ]*]' file
RegEx Details:
\[: Match a[[^] ]*: Match 0 or more of any chars that are not]and space[^]]*: Match 0 or more of any chars that are not]]: Match a]
Problem with .* is that it matches 0 or more of any character except a line break. It won't stop at ].