There are often times I will grep -n whatever file to find what I am looking for. Say the output is:
1234: whatev 1
5555: whatev 2
6643: whatev 3If 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 & head but that doesn't work out so well with log files that are constantly being written to.
7 Answers
Try using sed as mentioned on . For example use
sed '2,4!d' somefile.txtto print from the second line to the fourth line of somefile.txt. (And don't forget to check , sed is a wonderful tool.)
The following command will do what you asked for "extract the lines between 1234 and 5555" in someFile.
sed -n '1234,5555p' someFileIf I understand correctly, you want to find a pattern between two line numbers. The awk one-liner could be
awk '/whatev/ && NR >= 1234 && NR <= 5555' fileYou don't need to run grep followed by sed.
Perl one-liner:
perl -ne 'if (/whatev/ && $. >= 1234 && $. <= 5555) {print}' fileLine 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" filenamewhich 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.
Put this in a file and make it executable:
#!/usr/bin/env bash
start=`grep -n $1 < $3 | head -n1 | cut -d: -f1; exit ${PIPESTATUS[0]}`
if [ ${PIPESTATUS[0]} -ne 0 ]; then echo "couldn't find start pattern!" 1>&2 exit 1
fi
stop=`tail -n +$start < $3 | grep -n $2 | head -n1 | cut -d: -f1; exit ${PIPESTATUS[1]}`
if [ ${PIPESTATUS[0]} -ne 0 ]; then echo "couldn't find end pattern!" 1>&2 exit 1
fi
stop=$(( $stop + $start - 1))
sed "$start,$stop!d" < $3Execute the file with arguments (NOTE that the script does not handle spaces in arguments!):
- Starting grep pattern
- Stopping grep pattern
- File path
To use with your example, use arguments: 1234 5555 myfile.txt
Includes lines with starting and stopping pattern.
0If I want to then just extract the lines between 1234 and 5555, is there a tool to do that?
There is also ugrep, a GNU/BSD grep compatible tool but one that offers a -K option (or --range) with a range of line numbers to do just that:
ugrep -K1234,5555 -n '' somefile.logYou can use the usual GNU/BSD grep options and regex patterns (but it also offers a lot more such as -K.)
If you want lines instead of line ranges, you can do it with perl: eg. if you want to get line 1, 3 and 5 from a file, say /etc/passwd:
perl -e 'while(<>){if(++$l~~[1,3,5]){print}}' < /etc/passwd
