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I wanted to extract the IPs under [abc] from file1, and use them to replace the list of hosts in file 2:

File1:

[abc]
192.168.29.153
192.168.29.155
[def]
192.168.29.153
[xyz]
192.168.29.153

File 2:

output.logstash:
  # The Logstash hosts
  hosts: ["192.168.29.115:5044"]

  # Optional SSL. By default is off.
  # List of root certificates for HTTPS server verifications
  #ssl.certificate_authorities: ["/etc/pki/root/ca.pem"]

  # Certificate for SSL client authentication
  #ssl.certificate: "/etc/pki/client/cert.pem"
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4
  • what goes where? I don't see any connection between "abc" or "192.168.29.153" or "192.168.29.115" ... Commented Feb 5, 2018 at 19:19
  • I want to extract the lines below [abc] : 192.168.29.153 192.168.29.155 and put them in the second file on the list of hosts just like that: hosts: ["192.168.29.153","192.168.29.155"] Commented Feb 5, 2018 at 19:21
  • Why does the .115 host have a port with it? Do they all need that port added? Commented Feb 5, 2018 at 19:49
  • yes, but I can add it manually on the file. No problem with that Commented Feb 5, 2018 at 19:51

1 Answer 1

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0

I think this does it, if awk is ok.

#! /usr/bin/awk -f

# here, NR is record number, and FNR is *file* record number - this matches only 
# in first file
NR == FNR {
    # if first field matches
    if ($1 ~ /abc/) {
        # arrange addresses with `", "` between them
        abc=$2
        for (i=3; i<=NF; i++) abc = abc "\", \"" $i
    } 
    # then we're finished with this file.
    next;
}

$1 ~ /hosts/ {
    # print the saved addresses formatted with `["` addr `"]`
    printf "  %s [\"%s\"]\n", $1, abc ;
    next
 }

# print any other lines with no editing.
{ print }

Gives output for the updated file as the below. Note that the built in variable RS (record seperator) is being updated between files though, to treat each separately.

~$ ./log_edit RS='[' hosts RS='\n' logstash
output.logstash:
  # The Logstash hosts
   hosts: ["192.168.29.153", "192.168.29.155"]

  # Optional SSL. By default is off.
  # List of root certificates for HTTPS server verifications
  #ssl.certificate_authorities: ["/etc/pki/root/ca.pem"]

  # Certificate for SSL client authentication
  #ssl.certificate: "/etc/pki/client/cert.pem

You'll also need to save the output then replace the old file.

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  • oh, I didn't see that there had been a change to the question.. Commented Feb 5, 2018 at 19:28
  • sorry yes.. because it a list of IPs not only one Commented Feb 5, 2018 at 19:32
  • I tried to run the awk command like that : awk script_awk fileabc filehosts but nothing was changed on the filehosts ... still hosts: ["192.168.29.115:5044"] Commented Feb 5, 2018 at 20:04
  • You need to call it like it is in the example, including the RS='...' file1 RS='...' file2. Otherwise it's not using the correct idea of a record. THe first file treats between [ characters like a line, almost. Commented Feb 5, 2018 at 20:07
  • Thank you so much ! but is it possible to put the new hosts line on the file logstash instead of the old line ? I mean apply the changes to the file itself and not to just display it on the output. Thx for your help ! Commented Feb 5, 2018 at 20:25

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