CODEWITHSUNDEEP
stringbashfileunixsed
Ero20
Ero20

Reputation: 13

Find string in file and delete two lines after

I'm quite new to bash and I'd like to know how to find a string in a file and delete two lines starting from this found string.

My file is formatted like this : 

username
pass
username2
pass2
username3
pass3

And I would like to delete one specific user for example :

./deleteftpuser username2

And have the file like 

username
pass
username3
pass3

I think I should use sed command but I don't know how should I use it.

Thanks a lot for helping !

Upvotes: 1

Views: 124

Answers (5)

Sundeep
Sundeep

Reputation: 23667

With GNU sed

$ cat ip.txt 
username
pass
username2
pass2
username3
pass3

$ sed '/username2/,+1d' ip.txt 
username
pass
username3
pass3

This searches for line matching username2 and then deletes that line plus one line after. Change it to +2 to delete two lines after and so on

Generic solution with perl

$ perl -ne 'if(/username2/){ $l = <> foreach(1..1) } else{ print }' ip.txt 
username
pass
username3
pass3

$ perl -ne 'if(/username2/){ $l = <> foreach(1..2) } else{ print }' ip.txt 
username
pass
pass3

$ # can also use: perl -pe 'if(/username2/){ undef $_; <> foreach(1..2) }' ip.txt
  • If line matches the given pattern, get lines after it as needed.
  • Otherwise, print input line

Upvotes: 0

heemayl
heemayl

Reputation: 42017

With GNU sed:

sed '/username2/ {N; d}' file.txt

With awk:

awk '/username2/ {np=1; next}; !np {print} np {np=0}' file.txt

Example:

% cat file.txt 
username
pass
username2
pass2
username3
pass3

% sed '/username2/ {N; d}' file.txt
username
pass
username3
pass3

% awk '/username2/ {np=1; next}; !np {print} np {np=0}' file.txt 
username
pass
username3
pass3

Upvotes: 1

James Brown
James Brown

Reputation: 37404

Yet another awk solution. p is only set if $0 or p is username2 and nextoccurs in that case:

$ awk '($0=="username2" || p=="username2") && p=$0 {next} 1' file
username
pass
username3
pass3

Upvotes: 0

Chem-man17
Chem-man17

Reputation: 1770

Grep solution-

$cat file

 username
 pass
 username2
 pass2
 username3
 pass3

grep -A 1 "username2" file > temp
grep -vf temp file

Store the search string and one line after it in file temp. Then get everything else from the file.

Output-

username
pass
username3
pass3

Upvotes: 0

P....
P....

Reputation: 18371

sed -e '/username2/ { N; d; }' infile
username
pass
username3
pass3

Upvotes: 0

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