How to show only next line after the matched one

Question

grep -A1  blah  logfile   Thanks to this command for every line that has  blah  in it  I get the output of the line that contains  blah  and the next line that follows in the logfile  It might be a simple one but I can t find a way to omit the line that has  blah  and only show next line in the output

User · Answer

It looks like you re using the wrong tool there   Grep isn t that sophisticated  I think you want to step up to awk as the tool for the job   awk   blah    getline  print  0    logfile  If you get any problems let me know  I think its well worth learning a bit of awk  its a great tool     p s   This example doesn t win a  useless use of cat award     http   porkmail org era unix award html

User · Answer

you can use grep  then take lines in jumps  grep -A1  blah  logfile   awk  NR 3  2   you can also take n lines after match  for example  seq 100   grep -A3  2   awk  NR 5  4  15 25 35 45 55 65 75 85 95 explanation -  here we want to grep all lines that are  2 and take 3 lines after it  which is  5  seq 100   grep -A3  2 will give you  12 13 14 15 -- 22 23 24 25 --     the number in the modulo  NR 5  is the added rows by grep  here it s 3 by the flag -A3    2 extra lines because you have current matching line and also the -- line that the grep is adding

User · Answer

you can try with awk   awk   blah  getline  print   logfile

User · Answer

perl one-liner alert just for fun    print only one line after match perl -lne   next       1  if  match          next  amp  amp  print  data txt  even more fun    print the next ten lines after match perl -lne  push  nexts       1       10   if  match          nexts  amp  amp  print  data txt  kinda cheating though since there s actually two commands

User · Answer

grep  Pattern    tail -n 2   head -n 1   Tail first 2 and then head last one to get exactly first line after match

User · Answer

Great answer from raim  was very useful for me  It is trivial to extend this to print e g  line 7 after the pattern  awk -v lines 7   blah   for i lines i --i getline  print  0    logfile

User · Answer

In general  I agree you re asking a lot of grep here  and that another tool may be the better solution  But in an embedded environment  I may not want to have sed or awk just to do this  I found the following solution works  as long as they re not contiguous matches    grep -A1 AT  CSQ wvdial out   grep -v AT  CSQ   Basically  match them  appending 1 line of context for each match  and then pipe that through an inverse match of your original pattern to strip those out  This of course means you can assume that your pattern doesn t show up in the  next  line

User · Answer

If that next lines never contain  blah   you can filter them with   grep -A1 blah logfile   grep -v blah   The use of cat logfile       is not needed

User · Answer

If you want to stick to grep  grep -A1  blah  logfile   grep -v  quot blah quot   or alternatively with sed  sed -n   blah  n p    logfile

User · Answer

I don t know of any way to do this with grep  but it is possible to use awk to achieve the same result   awk   blah   getline print    lt  logfile

User · Answer

Piping is your friend     Use grep -A1 to show the next line after a match  then pipe the result to tail and only grab 1 line    cat logs info log   grep  term  -A1   tail -n 1

User · Answer

Many good answers have been given to this question so far  but I still miss one with awk not using getline   Since  in general  it is not necessary to use getline  I would go for  awk   f  amp  amp  NR  f 1   blah   f NR   file   all matches after  quot blah quot   or awk   blah   f NR  f  amp  amp  NR  f 1  file    matches after  quot blah quot  not being also  quot blah quot   The logic always consists in storing the line where  quot blah quot  is found and then printing those lines that are one line after  Test Sample file    cat a 0 blah1 1 2 3 blah2 4 5 6 blah3 blah4 7  Get all the lines after  quot blah quot   This prints another  quot blah quot  if it appears after the first one    awk  f amp  amp NR  f 1   blah   f NR   a 1 4 blah4 7  Get all the lines after  quot blah quot  if they do not contain  quot blah quot  themselves    awk   blah   f NR  f  amp  amp  NR  f 1  a 1 4 7

[awk] How to show only next line after the matched one?

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