removing duplicate lines from a file

ocelot · #1 (**permalink**) 01-25-2007

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

Krrishv · #2 (**permalink**) 01-25-2007

grep -v "^t" <filename>

anbu23 · #3 (**permalink**) 01-25-2007

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

jim mcnamara · #4 (**permalink**) 01-25-2007

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.

ocelot · #5 (**permalink**) 01-25-2007

thanks guys that worked a treat!

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