Display a block of text: multi-line grep with perl

perl -ne 'print if /start_pattern/../stop_pattern/' file.txt
-n reads input, line by line, in a loop sending to $_ Equivalent to while () { mycode } -e execute the following quoted string (i.e. do the following on the same line as the perl command) the elipses .. operator behaves like a range, remembering the state from line to line.

2
By: SunKing2
2018-07-24 03:23:12

3 Alternatives + Submit Alt

  • I find this terribly useful for grepping through a file, looking for just a block of text. There's "grep -A # pattern file.txt" to see a specific number of lines following your pattern, but what if you want to see the whole block? Say, the output of "dmidecode" (as root): dmidecode | awk '/Battery/,/^$/' Will show me everything following the battery block up to the next block of text. Again, I find this extremely useful when I want to see whole blocks of text based on a pattern, and I don't care to see the rest of the data in output. This could be used against the '/etc/securetty/user' file on Unix to find the block of a specific user. It could be used against VirtualHosts or Directories on Apache to find specific definitions. The scenarios go on for any text formatted in a block fashion. Very handy.


    85
    awk '/start_pattern/,/stop_pattern/' file.txt
    atoponce · 2009-03-28 14:28:59 7

  • 7
    sed -n /start_pattern/,/stop_pattern/p file.txt
    pipping · 2009-10-24 16:35:39 1
  • By using vim, you can also filter content on stdout, using vim's extra power, like search pattern offset! No more awk of course, sorry. details : -e ex mode -s silent -c 'ex command' : global + start and end pattern + offset print (p) -cq : quit Show Sample Output


    0
    vim -e -s -c 'g/start_pattern/+1,/stop_pattern/-1 p' -cq file.txt
    syladmin · 2009-08-26 10:22:27 0

What Others Think

nice one
emphazer · 3 weeks and 2 days ago

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Any thoughts on this command? Does it work on your machine? Can you do the same thing with only 14 characters?

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