34.22. Uses of the sed Quit Command
It can take only a single-line address. Once the line matching address (line-address) is reached, the script will be terminated.
For instance, the following one-liner uses the quit command to print the first ten lines from a file:
% sed '10q' myfile ...
sed prints each line until it gets to line 10 and quits.
The previous version is much more efficient than its functional equivalent:
-n Section 34.3
% sed -n '1,10p' myfile
(especially if myfile is a long file) because sed doesn't need to keep reading its input once the patterns in the script are satisfied.
One possible use of q is to quit a script after you've extracted what you want from a file. There is some inefficiency in continuing to scan through a large file after sed has found what it is looking for.
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