I have text file with server URL lines like:
request get https://abc.net/search?q=hello/world/hello/word/search=5&size=10 request get https://abc.net/search?q=hello/world/hello/world/hello/word=5 In this text file, I want the text after the word "search?q=" string and store in another file output file:
hello/world/hello/word/search=5&size=10 hello/world/hello/word/hello/world=5 hello1world1/hello/world/hello/word 
sed -n '/search?q=/{s/.*search?q=//;p;}' infile > outfile Explanation:
/search?q=/ makes the following command set (in curly braces) apply only to lines containing this regex.
s/.*search?q=// substitutes the second part (empty) for the first part.
Then p prints the line.
The -n flag suppresses the default printing of the line.
Actually, you can simplify this like so:
sed -n '/.*search?q=/{s///;p;}' infile > outfile Because when the pattern fed to the s/ command is left blank, the last used pattern is used again.
EDIT: Thanks to RobertL for pointing out a simplification in the comments:
sed -n 's/.*search?q=//p' infile > outfile This uses the p flag to the s command, which only prints out the line if a substitution was made.
If your version of grep supports PCRE, you could use something like
grep -oP 'search\?q=\K.*' infile > outfile with perl based regex search using lookbehind we can get your required result.
grep -oP '(?<=search\?q\=)[^ ]*' *filename* remember to add \ before ? and = as those are part of lookbehind regex.
cut -d= -f2- <in >out