awk matching only 1 lines with same pattern

Question

The following awk script will add an entry SAMPLE to block NOTES. I have multiple blocks with the same name. What needs to be changed in this command to add the entry SAMPLE to first block NOTES only?

a class.txt with following content.

[serverClass:NOTES:new]
 whitelist.0=TEST
 whitelist.1=FRIDAY
 whitelist.2=SPOON
 whitelist.3=GAME29

[serverClass:NOTES]
 whitelist.0=TEST
 whitelist.1=FRIDAY
 whitelist.2=SPOON
 whitelist.3=GAME29

[serverClass:NOTES:new23]
 whitelist.0=TEST
 whitelist.1=FRIDAY
 whitelist.2=SPOON
 whitelist.3=GAME29sdf

after running this command

awk -vRS= -vORS='\n\n' '
  BEGIN{z="whitelist.0=SAMPLE";FS="\n"}
  /NOTES/{
    if (/[0-9]=/){
      split($NF, a, /[.=]/);
      sub(/0/, a[2]+1, z)
    }
    sub (/$/,"\n"z ,$0)
  };1' class.txt

output:

[serverClass:NOTES:new]
 whitelist.0=TEST
 whitelist.1=FRIDAY
 whitelist.2=SPOON
 whitelist.3=GAME29
 whitelist.4=SAMPLE    <-------

[serverClass:NOTES]
 whitelist.0=TEST
 whitelist.1=FRIDAY
 whitelist.2=SPOON
 whitelist.3=GAME29
 whitelist.4=SAMPLE    <-------

[serverClass:NOTES:new23]
 whitelist.0=TEST
 whitelist.1=FRIDAY
 whitelist.2=SPOON
 whitelist.3=GAME29sdf
 whitelist.4=SAMPLE    <-------

what need to be changed in above awk command to add to the block match [serverClass:NOTES] only?

expected:

[serverClass:NOTES:new]
 whitelist.0=TEST
 whitelist.1=FRIDAY
 whitelist.2=SPOON
 whitelist.3=GAME29

[serverClass:NOTES]
 whitelist.0=TEST
 whitelist.1=FRIDAY
 whitelist.2=SPOON
 whitelist.3=GAME29
 whitelist.4=SAMPLE    <-------  should be

[serverClass:NOTES:new23]
 whitelist.0=TEST
 whitelist.1=FRIDAY
 whitelist.2=SPOON
 whitelist.3=GAME29sdf

Please don't change the requirements of your question after posting it. This is not the same question you had asked before. You need to post a new question each time you need something different. — terdon
– terdon ♦, Commented Mar 1, 2016 at 19:16
OP, in this case you should simply use /NOTES]/ instead of /NOTES/. — don_crissti
– don_crissti, Commented Mar 1, 2016 at 19:19

terdon · Accepted Answer · 2016-03-01 19:07:54Z

2

The simplest approach is to use a variable and set its value to 1 the first time NOTES is found. Then, tell your script to only add the new entry if the variable is not 1. For example:

awk -vRS= -vORS='\n\n' '
  BEGIN{z="whitelist.0=SAMPLE";FS="\n"}
  /NOTES/ && flag!=1{
    if (/[0-9]=/){
      split($NF, a, /[.=]/);
      sub(/0/, a[2]+1, z);
      flag=1;
    }
    sub (/$/,"\n"z ,$0)
  };1' infile

answered Mar 1, 2016 at 19:07

terdon♦

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