Since not all regex flavors support lookbehind, Perl introduced the \K. In general when you have: a\Kb When “b” is matched, \K tells the engine to pretend that the match attempt started at this position. In your example, you want to pretend that the match attempt started at what appears after the “access_token”:” text. This … Read more
If you want to wait for jobs to finish, use wait. This will make the shell wait until all background jobs complete. However, if any of your jobs daemonize themselves, they are no longer children of the shell and wait will have no effect (as far as the shell is concerned, the child is already … Read more
Use tr ‘\n’ ‘ ‘ to translate all newline characters to spaces: $ grep pattern file | tr ‘\n’ ‘ ‘ Note: grep reads files, cat concatenates files. Don’t cat file | grep! Edit: tr can only handle single character translations. You could use awk to change the output record separator like: $ grep pattern … Read more
When using nohup and you put the task in the background, the background operator (&) will give you the PID at the command prompt. If your plan is to manually manage the process, you can save that PID and use it later to kill the process if needed, via kill PID or kill -9 PID … Read more
Here are some ways to do it: grep –color ‘pattern\|$’ file grep –color -E ‘pattern|$’ file egrep –color ‘pattern|$’ file The | symbol is the OR operator. Either escape it using \ or tell grep that the search text has to be interpreted as regular expressions by adding -E or using the egrep command instead … Read more
Try grep -Fwf file2 file1 > out The -F option specifies plain string matching, so should be faster without having to engage the regex engine.
I believe the problem here is that the first grep is buffering the output which means the second grep won’t see it until the buffer is flushed. Try adding the –line-buffered option on your first grep: tail -f access_log | grep –line-buffered “127.0.0.1” | grep -v “.css” For more info, see “BashFAQ/009 — What is … Read more
You want the -w option to specify that it’s the end of a word. find . | xargs grep -sw ‘s:text’
This works for multiple occurrences per line: grep -o string * | wc -l
Assuming you have gnu grep, you can use perl-style regex to do a positive lookbehind: grep -oP ‘(?<=GET\s/)\w+’ file If you don’t have gnu grep, then I’d advise just using sed: sed -n ‘/^.*GET[[:space:]]\{1,\}\/\([-_[:alnum:]]\{1,\}\).*$/s//\1/p’ file If you happen to have gnu sed, that can be greatly simplified: sed -n ‘/^.*GET\s\+\/\(\w\+\).*$/s//\1/p’ file The bottom line here … Read more