How to get the part of a file after the first line that matches a regular expression

Question

I have a file with about 1000 lines  I want the part of my file after the line which matches my grep statement   That is     cat file   grep  TERMINATE        It is found on line 534   So  I want the file from line 535 to line 1000 for further processing   How can I do that

User · Answer

If for any reason  you want to avoid using sed  the following will print the line matching TERMINATE till the end of the file   tail -n     grep -n  TERMINATE  file   head -n 1   cut -d     -f 1   file   and the following will print from the following line matching TERMINATE till the end of the file   tail -n        grep -n  TERMINATE  file   head -n 1   cut -d     -f 1  1    file   It takes 2 processes to do what sed can do in one process  and if the file changes between the execution of grep and tail  the result can be incoherent  so I recommend using sed   Moreover  if the file dones not contain TERMINATE  the 1st command fails

User · Answer

Use bash parameter expansion like the following   content   cat file  echo    content  TERMINATE

User · Answer

As a simple approximation you could use  grep -A100000 TERMINATE file   which greps for TERMINATE and outputs up to 100000 lines following that line   From man page     -A NUM  --after-context NUM      Print  NUM  lines  of  trailing  context  after  matching lines    Places  a  line  containing  a  group  separator   --    between   contiguous  groups  of  matches   With the -o or --only-matching   option  this has no effect and a warning is given

User · Answer

grep -A 10000000  TERMINATE  file          is much  much faster than sed especially working on really big file   It works up to 10M lines  or whatever you put in  so no harm in making this big enough to handle about anything you hit

User · Answer

If I understand your question correctly you do want the lines after TERMINATE  not including the TERMINATE-line  awk can do this in a simple way   awk   if found  print   TERMINATE  found 1   your file   Explanation    Although not best practice you could rely on the fact that all vars defaults to 0 or the empty string if not defined  So the first expression  if found  print  will not print anything to start off with  After the printing is done we check if the this is the starter-line  that should not be included     This will print all lines after the TERMINATE-line     Generalization    You have a file with start- and end-lines and you want the lines between those lines excluding the start- and end-lines  start- and end-lines could be defined by a regular expression matching the line    Example     cat ex file txt  not this line second line START A good line to include And this line Yep END Nope more     never ever   awk   END  found 0   if found  print   START  found 1   ex file txt  A good line to include And this line Yep     Explanation    If the end-line is found no printing should be done  Note that this check is done before the actual printing to exclude the end-line from the result  Print the current line if found is set  If the start-line is found then set found 1 so that the following lines are printed  Note that this check is done after the actual printing to exclude the start-line from the result    Notes    The code rely on the fact that all awk-vars defaults to 0 or the empty string if not defined  This is valid but may not be best practice so you could add a BEGIN found 0  to the start of the awk-expression  If multiple start-end-blocks is found they are all printed

User · Answer

sed is a much better tool for the job      sed -n   re   p  file  where re is regexp   Another option is grep s --after-context flag  You need to pass in a number to end at  using wc on the file should give the right value to stop at  Combine this with -n and your match expression

User · Answer

This could be a one way of doing it  If you know what line of the file you have your grep word and how many lines you have in your file   grep -A466  TERMINATE  file

User · Answer

There are many ways to do it with sed or awk   sed -n   TERMINATE   p  file   This looks for TERMINATE in your file and prints from that line up to the end of the file   awk   TERMINATE  0  file   This is exactly the same behaviour as sed   In case you know the number of the line from which you want to start printing  you can specify it together with NR  number of record  which eventually indicates the number of the line    awk  NR gt  535  file   Example    seq 10  gt  a         generate a file with one number per line  from 1 to 10   sed -n   7   p  a 7 8 9 10   awk   7  0  a 7 8 9 10   awk  NR gt  7  a 7 8 9 10

User · Answer

The following will print the line matching TERMINATE till the end of the file   sed -n -e   TERMINATE   p    Explained  -n disables default behavior of sed of printing each line after executing its script on it  -e indicated a script to sed   TERMINATE    is an address  line  range selection meaning the first line matching the TERMINATE regular expression  like grep  to the end of the file      and p is the print command which prints the current line   This will print from the line that follows the line matching TERMINATE till the end of the file   from AFTER the matching line to EOF  NOT including the matching line   sed -e  1  TERMINATE d    Explained  1  TERMINATE  is an address  line  range selection meaning the first line for the input to the 1st line matching the TERMINATE regular expression  and d is the delete command which delete the current line and skip to the next line   As sed default behavior is to print the lines  it will print the lines after TERMINATE  to the end of input   Edit   If you want the lines before TERMINATE   sed -e   TERMINATE   d    And if you want both lines before and after TERMINATE in 2 different files in a single pass   sed -e  1  TERMINATE w before  TERMINATE   w after  file   The before and after files will contain the line with terminate  so to process each you need to use   head -n -1 before tail -n  2 after   Edit2   IF you do not want to hard-code the filenames in the sed script  you can   before before txt after after txt sed -e  1  TERMINATE w  before  TERMINATE    w  after  file   But then you have to escape the   meaning the last line so the shell will not try to expand the  w variable  note that we now use double quotes around the script instead of single quotes    I forgot to tell that the new line is important after the filenames in the script so that sed knows that the filenames end    Edit  2016-0530  S  bastien Cl  ment asked   How would you replace the hardcoded TERMINATE by a variable    You would make a variable for the matching text and then do it the same way as the previous example     matchtext TERMINATE before before txt after after txt sed -e  1   matchtext w  before   matchtext    w  after  file   to use a variable for the matching text with the previous examples      Print the line containing the matching text  till the end of the file      from the matching line to EOF  including the matching line  matchtext TERMINATE sed -n -e    matchtext    p         Print from the line that follows the line containing the     matching text  till the end of the file      from AFTER the matching line to EOF  NOT including the matching line  matchtext TERMINATE sed -e  1   matchtext d         Print all the lines before the line containing the matching text      from line-1 to BEFORE the matching line  NOT including the matching line  matchtext TERMINATE sed -e    matchtext    d    The important points about replacing text with variables in these cases are      Variables   variablename  enclosed in single quotes     won t  expand  but variables inside double quotes     will  So  you have to change all the single quotes to double quotes if they contain text you want to replace with a variable    The sed ranges also contain a   and are immediately followed by a letter like   p   d   w  They will also look like variables to be expanded  so you have to escape those   characters with a backslash     like    p    d    w

User · Answer

A tool to use here is awk   cat file   awk  BEGIN  found 0   TERMINATE  found 1    if  found  print      How does this work    We set the variable  found  to zero  evaluating false if a match for   TERMINATE  is found with the regular expression  we set it to one  If our  found  variable evaluates to True  print      The other solutions might consume a lot of memory if you use them on very large files

User · Answer

These will print all lines from the last found line  TERMINATE  till end of file   LINE NUMBER  grep -o -n TERMINATE  OSCAM LOG tail -n 1 sed  s        g  awk -F      print  1    tail -n   LINE NUMBER  YOUR FILE NAME

User · Answer

Alternatives to the excellent sed answer by jfgagne  and which don t include the matching line     awk   TERMINATE   y 1 next  y    https   stackoverflow com a 18166628   awk   TERMINATE    c     c    https   stackoverflow com a 23984891   perl -ne  print unless 1     TERMINATE     https   stackoverflow com a 18167194

[bash] How to get the part of a file after the first line that matches a regular expression?

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