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How to get lines with only one occurence of pattern?

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# 1  
Old 12-21-2016
How to get lines with only one occurence of pattern?
My data
Code:
20161220 20:30:01 MODE 1 TEST 1 SOURCE 1 SET 1
20161220 20:30:02 MODE 1 TEST 2 SOURCE 1 SET 1
20161220 20:30:02 MODE 1 TEST 3 SOURCE 1 SET 1
20161220 20:30:02 MODE 1 TEST 1 SOURCE 2 SET 1
20161220 20:30:04 MODE 1 TEST 1 SOURCE 1 SET 1 MODE 1 TEST 2 SOURCE 2 SET 1
20161220 20:30:02 MODE 2 TEST 2 SOURCE 1 SET 1
20161220 20:30:06 MODE 1 TEST 1 SOURCE 1 SET 1 MODE 2 TEST 2 SOURCE 2 SET 1

To get lines with more than one MODE I do this:
Code:
$ sed -n '/MODE.*MODE/p' aa
20161220 20:30:04 MODE 1 TEST 1 SOURCE 1 SET 1 MODE 1 TEST 2 SOURCE 2 SET 1
20161220 20:30:06 MODE 1 TEST 1 SOURCE 1 SET 1 MODE 2 TEST 2 SOURCE 2 SET 1

Now I need to get only lines with single occurrence of MODE. Before I start writing an awk counting these MODE keywords, is there a "proper" way with just a regular expression?
# 2  
Old 12-21-2016
If all lines contain MODE as shown:
Code:
$ sed -n '/MODE.*MODE/!p' aa

This User Gave Thanks to Aia For This Post:
rbatte1
# 3  
Old 12-21-2016
For must contain MODE but not MODE.*MODE

Code:
sed -n '/MODE/!d;/MODE.*MODE/!p' aa


or you could use 2 greps:

Code:
grep "MODE" aa | grep -v "MODE.*MODE"

This User Gave Thanks to Chubler_XL For This Post:
rbatte1
# 4  
Old 12-21-2016
Some alternatives with Perl.

Display only lines with one MODE
Code:
perl -ne 'print if (()=/MODE/g) == 1' migurus.file

Display only lines with two MODE
Code:
perl -ne 'print if (()=/MODE/g) == 2' migurus.file

Display any line that do not have only two MODE
Code:
perl -ne 'print if (()=/MODE/g) != 2' migurus.file

Display any line with zero or one MODE
Code:
perl -ne 'print if (()=/MODE/g) < 2' migurus.file

Last edited by Aia; 12-21-2016 at 11:43 PM..
# 5  
Old 12-22-2016
Hi Aia , could you please explain below highlighted part of code.
Code:
perl -ne 'print if (()=/MODE/g) == 1' migurus.file

# 6  
Old 12-22-2016
You cannot do this with a single basic regular expression. You need to either count the number like some solutions do or use multiple regexes.

A variation on Chubler XL's approach with two regexes:
Code:
sed '/MODE.*MODE/d; /MODE/!d' file

Or counting the number of occurrences:
Code:
awk -FMODE 'NF==2' file

Last edited by Scrutinizer; 12-22-2016 at 05:02 AM..
This User Gave Thanks to Scrutinizer For This Post:
migurus
# 7  
Old 12-22-2016
Quote:
Originally Posted by looney
Hi Aia , could you please explain below highlighted part of code.
Code:
perl -ne 'print if (()=/MODE/g) == 1' migurus.file

The parenthesis is a list context of the matches from the regex which the evaluation uses back in scalar context.

Written in another way:
Code:
 perl -ne '@match_list = $_ =~ m/MODE/g; print $_ if (scalar @match_list) == 1' migurus.file
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