How to delete all text before some string

Question

Recently, I found this solution, it worked for me because I always used this command with some date and hour, that is, the string almost always unique in my case.

sed -n -i '/some_string_here/,$p' file_here

But recently I needed to use other kind of string (no date and hour)

The problem is, this solution only work from the first ocorrence up

[oracle@server1 ~]$ cat arquivo
OPERATIONAL SYSTEMS:
Windows
MAC OS
OPERATIONAL SYSTEMS TOMORROW:
Linux
Xubunto
OPERATIONAL SYSTEMS TOMORROW:
AIX
SOLARIS

[oracle@server1 ~]$ sed -n -i '/OPERATIONAL SYSTEMS TOMORROW:/,$p' arquivo
[oracle@server1 ~]$ cat arquivo
OPERATIONAL SYSTEMS TOMORROW:
Linux
Xubunto
OPERATIONAL SYSTEMS TOMORROW:
AIX
SOLARIS

I need to do something like this to print from the last occurrence of OPERATIONAL SYSTEMS TOMORROW: until the end.

[oracle@server1 ~]$ cat arquivo
OPERATIONAL SYSTEMS:
Windows
MAC OS
OPERATIONAL SYSTEMS TOMORROW:
Linux
Xubunto
OPERATIONAL SYSTEMS TOMORROW:
AIX
SOLARIS

[oracle@server1 ~]$ sed -n -i 'some command for it' arquivo
[oracle@server1 ~]$ cat arquivo
OPERATIONAL SYSTEMS TOMORROW:
AIX
SOLARIS

How can I do it?

Answer 1

Here is a one-liner with sed:

sed -n 'H; /^OPERATIONAL SYSTEMS TOMORROW:/h; ${g;p;}' arquivo

Output:

OPERATIONAL SYSTEMS TOMORROW:
AIX
SOLARIS

To edit the file in place:

sed -i -n 'H; /^OPERATIONAL SYSTEMS TOMORROW:/h; ${g;p;}' arquivo

Answer 2

Swap the order of the lines in the file, get the first few lines, then swap these again:

$ tac file | sed '/OPERATIONAL SYSTEMS TOMORROW:/q' | tac
OPERATIONAL SYSTEMS TOMORROW:
AIX
SOLARIS

This would possibly not be efficient, but it's simple, and therefore understandable and maintainable.

The tac utility is part of GNU coreutils.

Answer 3

You can do this in pure sh using

${VAR%%string}

Where $VAR contains the text you want to process

Answer 4

Using aned one-liner:

printf "%s\n" '?^OPERATIONAL SYSTEMS TOMORROW:$?,$w' | ed -s arquivo

or with ex instead:

ex -sc '?^OPERATIONAL SYSTEMS TOMORROW:$?,$wq!' input.txt

these rewrite arquivo to save only everything from the last matching line to the end of the file.

Using a file-oriented tool like ed or ex instead of a stream-oriented one like sed or awk makes many non-trivial automated editing tasks much simpler because they can do things like search backwards from a cursor location.

Answer 5

Using perl (maybe faster than awk and sed):

$ cat temp.txt
OPERATIONAL SYSTEMS:
Windows
MAC OS
OPERATIONAL SYSTEMS TOMORROW:
Linux
Xubunto
Extra
OPERATIONAL SYSTEMS:
Windows
MAC OS
OPERATIONAL SYSTEMS TOMORROW:
AIX
SOLARIS  

Execute:

$ perl -ne ' {
  if ( $_ =~ /(OPERATIONAL SYSTEMS TOMORROW:)/ ) {$found=1;$index=0;}
  if($found ) {$index++; $a[$index]=$_;} $last_index=$index;}
  END {
  for($i=1;$i<=$index;$i++){ print $a[$i];}
  } ' temp.txt