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Suppose i have a file with many words, i want to find only the first word with the pattern "xyz". How do I do it if there are multiple words with this pattern on the same line? -m returns all the words in the first line in which it matches. I need only grep command.

dr_
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Atchyut Sreekar
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  • Do you have many lines in your file? Do you want to find the first word in whole file or the first word in each line? – Arkadiusz Drabczyk Apr 12 '17 at 11:54
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    it looks like you're asking people to provide you the full command.That's not really how unix.stackexchange works. You should show what you've done, and where you're stuck – Modassir Haider Apr 12 '17 at 12:02

2 Answers2

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By default grep prints the lines matching a pattern, so if the pattern appears one or more times into a line, grep will print that whole line.

Adding the flag -m 7 will tell grep to print only the first 7 lines where the pattern appears.

So this should do what you want (I haven't tested it):

grep -o -m 1 xyz myfile | head -1

Edit: as pointed out by @Kusalananda, you don't strictly need the -m flag but using it means grep won't need to parse the whole file, and will output the result faster, especially if myfile is a large file.

dr_
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  • Okay. If I assume there is only one such word per line, grep -o -m 1 "exp" filename would do my job right? – Atchyut Sreekar Apr 12 '17 at 11:40
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    @AtchyutSreekar No, that would'nt, it would fetch all the matching patterns from te first line. You need to pipe that to head -1 to get the real first. –  Apr 12 '17 at 11:54
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    The `-m 1` is not needed. The matches returned by `-o` will be on separate lines and `head -1` will pick the first match. Removing `-m 1` will make `grep` go through the entire file (or stop when it notices that it can't write to stdout any longer because `head` has exited), but it make it portable to other Unices that don't have the `-m` flag (BSD). – Kusalananda Apr 12 '17 at 12:22
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The answer to your question is in the grep man page:

grep -m1 'searchstring' file_name

The -m<number> option is the key. -m1 will only show the first match, -m2 the first 2 occurrences and so on.

Stephen Kitt
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Med Saleh Mdini
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