Grep characters before and after match

Question

Using this   grep -A1 -B1  test pattern  file   will produce one line before and after the matched pattern in the file  Is there a way to display not lines but a specified number of characters    The lines in my file are pretty big so I am not interested in printing the entire line but rather only observe the match in context  Any suggestions on how to do this

User · Answer

With gawk   you can use match function       x  hey there how are you      echo   x   awk --re-interval   match  0     4  how   4    a  print a 1  a 2        ere   are   If you are ok with perl  more flexible solution   Following will print three characters before the pattern followed by actual pattern and then 5 character after the pattern    echo hey there how are you  perl -lne  print   1 2 3  if     3   there    5     ey there how   This can also be applied to words instead of just characters Following will print one word before the actual matching string    echo hey there how are you  perl -lne  print  1 if    w   there   hey   Following will print one word after the pattern   echo hey there how are you  perl -lne  print  2 if    w   there   w     how   Following will print one word before the pattern   then the actual word and then one word after the pattern   echo hey there how are you  perl -lne  print   1 2 3  if    w    there    w     hey there how

User · Answer

I ll never easily remember these cryptic command modifiers so I took the top answer and turned it into a function in my    bashrc file    cgrep           For files that are arrays 10 s of thousands of characters print        Use cpgrep to print 30 characters before and after search patttern      if      -eq 2     then           Format was  cgrep  quot search string quot   path to filename          grep -o -P  quot   0 30  1  0 30  quot   quot  2 quot      else           Format was  cat  path to filename   cgrep  quot search string quot          grep -o -P  quot   0 30  1  0 30  quot      fi     cgrep    Here s what it looks like in action    ll  tmp rick scp Mf7UdS Mf7UdS Source  -rw-r--r-- 1 rick rick 25780 Jul  3 19 05  tmp rick scp Mf7UdS Mf7UdS Source    cat  tmp rick scp Mf7UdS Mf7UdS Source   cgrep  quot Link to iconic quot   1 43 30 3540244000  mnt e bin Link to iconic S -rwxrwxrwx 777 rick 1000 ri    cgrep  quot Link to iconic quot   tmp rick scp Mf7UdS Mf7UdS Source  1 43 30 3540244000  mnt e bin Link to iconic S -rwxrwxrwx 777 rick 1000 ri   The file in question is one continuous 25K line and it is hopeless to find what you are looking for using regular grep  Notice the two different ways you can call cgrep that parallels grep method  There is a  quot niftier quot  way of creating the function where  quot  2 quot  is only passed when set which would save 4 lines of code  I don t have it handy though  Something like   parm2   parm2  If I find it I ll revise the function and this answer

User · Answer

grep -E -o    0 5 test pattern  0 5   test txt    This will match up to 5 characters before and after your pattern  The -o switch tells grep to only show the match and -E to use an extended regular expression  Make sure to put the quotes around your expression  else it might be interpreted by the shell

User · Answer

You could use  awk   test pattern        match  0   test pattern    print substr  0  RSTART - 10  RLENGTH   20      file

User · Answer

3 characters before and 4 characters after    gt  echo  some123 string and another    grep -o -P    0 3 string  0 4   23 string and

User · Answer

You can use regexp grep for finding   second grep for highlight  echo  some123 string and another    grep -o -P    0 3 string  0 4     grep string   23 string and

User · Answer

You mean  like this   grep -o     0 20  test pattern   0 20    file      That will print up to twenty characters on either side of test pattern  The   0 20   notation is like    but specifies zero to twenty repetitions instead of zero or more The -o says to show only the match itself  rather than the entire line

[bash] Grep characters before and after match?

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