removing duplicate lines from a file


 
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# 1  
removing duplicate lines from a file

Hi,

I am trying to remove duplicate lines from a file. For example the contents of example.txt is:

this is a test
2342
this is a test
34343
this is a test
43434

and i want to remove the "this is a test" lines only and end up with the numbers in the file, that is, end up with:

2342
34343
43434

thanks
# 2  
grep -v "^t" <filename>
# 3  
Quote:
Originally Posted by ocelot
Hi,

I am trying to remove duplicate lines from a file. For example the contents of example.txt is:

this is a test
2342
this is a test
34343
this is a test
43434

and i want to remove the "this is a test" lines only and end up with the numbers in the file, that is, end up with:

2342
34343
43434

thanks
Code:
grep -v "[[:alpha:]]" file

# 4  
Code:
# this prints only one line for each distinct record in oldfile
awk '!x[$0]++' oldfile > newfile

# this completely removes all occurrances of all duplicated lines
awk 'x[$0]++ == 2' oldfile > t.sed
grep -v -f t.sed  oldfile > newfile

The other given solutions are data dependent, ie., using the special characteristics of duplicated data in your example to filter.
# 5  
thanks guys that worked a treat! Smilie
 

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