How to grep out specific line ranges of a file

Question

There are often times I ll grep -n whatev file to find what I m looking for   Say the output is  1234  whatev 1 5555  whatev 2 6643  whatev 3   If I want to then just extract the lines between 1234 and 5555  is there a tool to do that   For static files I have a script that does wc -l of the file and then does the math to split it out with tail  amp  head but that doesn t work out so well with log files that are constantly being written to

User · Answer

Line numbers are OK if you can guarantee the position of what you want. Over the years, my favorite flavor of this has been something like this:

sed "/First Line of Text/,/Last Line of Text/d" filename

which deletes all lines from the first matched line to the last match, including those lines.

Use sed -n with "p" instead of "d" to print those lines instead. Way more useful for me, as I usually don't know where those lines are.

User · Answer

If you want lines instead of line ranges  you can do it with perl  eg  if you want to get line 1  3 and 5 from a file  say  etc passwd   perl -e  while  lt  gt   if    l   1 3 5   print     lt   etc passwd

User · Answer

Put this in a file and make it executable      bin bash start  grep -n  1  lt   3   head -n1   cut -d  -f1  exit   PIPESTATUS 0    if     PIPESTATUS 0   -ne 0    then     echo  couldn t find start pattern   1 gt  amp 2     exit 1 fi stop  tail -n   start  lt   3   grep -n  2   head -n1   cut -d  -f1  exit   PIPESTATUS 1    if     PIPESTATUS 0   -ne 0    then     echo  couldn t find end pattern   1 gt  amp 2     exit 1 fi  stop      stop    start - 1    sed   start  stop d   lt   3   Execute the file with arguments  NOTE that the script does not handle spaces in arguments      Starting grep pattern Stopping grep pattern File path   To use with your example  use arguments  1234 5555 myfile txt  Includes lines with starting and stopping pattern

User · Answer

If I understand correctly  you want to find a pattern between two line numbers   The awk one-liner could be  awk   whatev   amp  amp  NR  gt   1234  amp  amp  NR  lt   5555  file   You don t need to run grep followed by sed   Perl one-liner   perl -ne  if   whatev   amp  amp      gt   1234  amp  amp      lt   5555    print   file

User · Answer

Try using sed as mentioned on  http   linuxcommando blogspot com 2008 03 using-sed-to-extract-lines-in-text-file html  For example use   sed  2 4 d  somefile txt   to print from the second line to the fourth line of somefile txt   And don t forget to check http   www grymoire com Unix Sed html  sed is a wonderful tool

User · Answer

The following command will do what you asked for  extract the lines between 1234 and 5555  in someFile   sed -n  1234 5555p  someFile

[command-line] How to "grep" out specific line ranges of a file

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