Q:
Grep a variable length file in UNIX based on tilde delimiter
Hello:
I need to grep a variable length UNIX file. This is a tilde delimited, 21 field file and I need to search for specific values in the 5th field.
Please help. My UNIX knowledge is not very extensive.
Thanks
I need to grep a variable length UNIX file. This is a tilde delimited, 21 field file and I need to search for specific values in the 5th field.
Please help. My UNIX knowledge is not very extensive.
Thanks
ASKED:
Jun 5 2008 7:27 PM GMT
A:
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cut -d~ -f5 foo | grep bar
To get the whole corresponding line:
egrep '*~*~*~*~*bar*~' foo
Hmmm... the regexp needs some tuning.
Say your file has lines like:
aaa~bbb~cccc~dd~this~www
where "aaa", "bbb" ... are anything w/o "~"s.
You want to find lines with "this" then the regexp for four "anything" and a "~" is (untested):
[^~]*~\{4}The breakdown: if
[abc]matches a single character a, b or c
[^abc]is any single character but a, b or c
then
[^~]is "not a tilde"
[^~]*is it zero or more times
[^~]*~is it plus a tilde
[^~]*~\{4} is it four timesNow, you said "specific valueS" in col #5, and the regexp looks only for "this".
To look for "this", "that" and "what" the regexp is:
\(this\|that\|what\)
The escaped parenthesis is to make it atomic, a single nugget, not sure if they are needed, not sure if your program will need the escaping slashes.
The escaped "|" are to separate alternatives. Again, your grep might not need the escaping slashes.
All together now:
[^~]*~\{4}\(this\|that\|what\)~Will look for "this", "that" and "what" in the 5th element and a ~ closing this element if it's not the last one.
This is to avoid selecting, for example, "thisRexExpSucks".
--
Juan Lanus
