Use grep to report back only line numbers

Question

I have a file that possibly contains bad formatting  in this case  the occurrence of the pattern   backslash   I would like to use grep to return only the line numbers where this occurs  as in  the match was here  go to line   x and fix it    However  there doesn t seem to be a way to print the line number  grep -n  and not the match or line itself   I can use another regex to extract the line numbers  but I want to make sure grep cannot do it by itself  grep -no comes closest  I think  but still displays the match

User · Answer

You re going to want the second field after the colon  not the first   grep -n  text to find  file txt   cut -f2 -d

User · Answer

using only grep   grep -n  text to find  file ext   grep -Po

User · Answer

try   grep -n  text to find  file ext   cut -f1 -d

User · Answer

To count the number of lines matched the pattern   grep -n  Pattern  in file ext   wc -l    To extract matched pattern  sed -n   pattern p  file est   To display line numbers on which pattern was matched  grep -n  pattern  file ext   cut -f1 -d

User · Answer

Bash version      lineno   grep -n  pattern  filename      lineno   lineno

User · Answer

All of these answers require grep to generate the entire matching lines  then pipe it to another program  If your lines are very long  it might be more efficient to use just sed to output the line numbers   sed -n   pattern    filename

User · Answer

I recommend the answers with sed and awk for just getting the line number  rather than using grep to get the entire matching line and then removing that from the output with cut or another tool  For completeness  you can also use Perl   perl -nE   pattern   amp  amp  say     filename   or Ruby   ruby -ne  puts    if  pattern   filename

User · Answer

If you re open to using AWK   awk   textstring   print FNR   textfile   In this case  FNR is the line number  AWK is a great tool when you re looking at grep cut  or any time you re looking to take grep output and manipulate it

[grep] Use grep to report back only line numbers

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