How to print only the first match with grep?

How to print only the first match with grep?

Yet, as @manatwork mentioned, shell built-in read or cut / sed / awk seem to be more appropriate (particularly once you get to the point you’d need to do something more). To show only the first match with grep, use -m parameter, e.g.: Stop reading the file after num matches. Why grep? The grep command is for searching.

How to find first match with extended regexp?

Reading the grep manual (man grep) this is the minimum command to find first match with Extended regexp. Example getting the ethernet name that in my laptop is NOT eth0 !

How to match first line in AST-open SED?

For matching the first, with ast-open’s sed whose EREs support the Perl-style *? non-greedy repetition operator: While loop in order to check each line separately. grep -o to get only the match instead of the whole line with matches.

Can a grep bring a match of 123 in every line?

Just a grep should be enough to bring matches of 123 in every line. It does not makes sense if the match is first ,middle or in the end. In case you need to catch with regex the first number of each row (any number – any length) then this will do the job:

When to ignore the F option in grep?

-f The -f option causes tail to not stop when end of file is reached, but rather to wait for additional data to be appended to the input. The -f option is ignored if the standard input is a pipe, but not if it is a FIFO. I’d like to only grep for something in the tail output.

Why does grep not stop when end of file is reached?

-f The -f option causes tail to not stop when end of file is reached, but rather to wait for additional data to be appended to the The -f option is ignored if the standard input is a pipe, but not if it is a FIFO. I’d like to only grep for somethingin the tail output. tail -f | grep

When to ignore the F option in tail?

Tail has the following options: -f The -f option causes tail to not stop when end of file is reached, but rather to wait for additional data to be appended to the input. The -f option is ignored if the standard input is a pipe, but not if it is a FIFO. I’d like to only grep for something in the tail output.

Is there way to tell grep to output only specified groupings?

Is there a way to tell grep to only output the items that match the grouping (or a specific grouping) in a regular expression? GNU grep has the -P option for perl-style regexes, and the -o option to print only what matches the pattern.

How to print only matching group Stack Overflow?

Will result in output of: 2 3.4 -f selects the range of ‘fields’ to output, in this case, it’s the 6th through 7th chunks of the original string. You can also specify the range as a list, such as 6,7. I agree with @kent that this is well suited for grep -o.

How can I print only the section that matches the regex in the group?

How can I print only the section of the line that matches the regex in the group? Match the whole line, so add a .* at the beginning of your regex. This causes the entire line to be replaced with the contents of the group grep is the right tool for extracting.