bash - Capturing Groups From a Grep RegEx - Stack Overflow
The first capture group is stored in index 1, the second (if any) in index 2, etc. Index zero is the full match. side note #1 regarding regex anchors: You should be aware that without anchors, this …
regex - Using the star sign in grep - Stack Overflow
Jul 6, 2016 · Please note that, according to POSIX, in basic regular expressions (BRE), the asterisk looses its special meaning when used as the first character of the BRE or right after …
regex - How to find patterns across multiple lines using grep?
Apr 22, 2010 · If the -z options specifies grep to treat newlines as zero byte characters then why do we need the (?s) in the regex ? If it is already a non-newline character, shouldn't . be able …
How to extract string following a pattern with grep, regex or perl
If you have an improved version of grep, such as GNU grep, you may have the -P option available. This option will enable Perl-like regex, allowing you to use \K which is a shorthand …
regex - How to use grep to extract a substring? - Stack Overflow
Sep 24, 2012 · With plain traditional grep, you cannot. Use grep -P with a lookahead if you have that (slightly challenging) or switch to sed or awk or Perl or Python.
How do I recursively grep all directories and subdirectories?
Feb 16, 2016 · If you are going to pipe find through xargs to grep, AND if you are only searching for a fixed string (i.e., not a regex), you might benefit from invoking the grep -F option, so grep …
How to print matched regex pattern using awk? - Stack Overflow
Apr 4, 2011 · Using awk, I need to find a word in a file that matches a regex pattern. I only want to print the word matched with the pattern. So if in the line, I have: xxx yyy zzz And pattern: /yyy/ …
How do you extract IP addresses from files using a regex in a linux ...
Everyone here is using really long-handed regular expressions but actually understanding the regex of POSIX will allow you to use a small grep command like this for printing IP addresses.
regex - Quotes when using grep? - Stack Overflow
Jun 9, 2010 · grep -e show\( test.txt So without quotes the backslash gets removed making the " (" a normal character for grep (grep uses basic regex by default, use -E to make grep use …
regex - grep egrep multiple-strings - Stack Overflow
Feb 24, 2014 · grep str1 | egrep ' (str2|str3)' you can do the "and" form in an order independent way using egrep, but I think you'll find it easier to remember to do order independent ands …