awk only change matching line and print rest of lines without modification-CodePudding

So I have a large file like the following:

RESOURCETAGMAPPINGLIST  arn:aws:ec2:us-east-1:XXXXXX:instance/i-XXXXXXXXXXXXXXXXX
TAGS    app-name    appname1
RESOURCETAGMAPPINGLIST  arn:aws:ec2:us-east-1:XXXXXX:instance/i-XXXXXXXXXXXXXXXXX
TAGS    app-name    appname2
RESOURCETAGMAPPINGLIST  arn:aws:ec2:us-east-1:XXXXXX:instance/i-XXXXXXXXXXXXXXXXX
TAGS    app-name    appname1
..

I only want to modify the line with RESOURCETAGMAPPINGLIST and print the the other lines w/out modification. Then I want to print only specific fields on the matching like, like below:

arn ec2 us-east-1 XXXXXX
TAGS    app-name    appname1
arn ec2 us-east-1 XXXXXX
TAGS    app-name    appname2
arn ec2 us-east-1 XXXXXX
TAGS    app-name    appname1
..

I was trying using awk gsub command, but really could not get the -F: part to work out. Any help would be greatly appreciated and it does not matter if it's awk, sed or perl.

CodePudding user response：

With awk. I used as input field separators at least one space ( ) or (|) one colon (:).

If a row contains string RESOURCETAGMAPPINGLIST then print columns 2, 4, 5, 6 and stop processing this row and continue with next row. If a row does not contain RESOURCETAGMAPPINGLIST then print complete row unchanged.

awk -F '  |:' '/RESOURCETAGMAPPINGLIST/{print $2,$4,$5,$6; next} {print}' file

Output:

arn ec2 us-east-1 XXXXXX
TAGS    app-name    appname1
arn ec2 us-east-1 XXXXXX
TAGS    app-name    appname2
arn ec2 us-east-1 XXXXXX
TAGS    app-name    appname1

See: The Stack Overflow Regular Expressions FAQ

CodePudding user response：

One awk idea using the default field delimiter and split():

awk '
/RESOURCETAGMAPPINGLIST/ { split($2,a,":")              # split 2nd field on ":" delimiter, storing results in array a[]
                           print a[1],a[3],a[4],a[5]
                           next                         # skip to next line of inpu
                         }
1                                                       # print current line
' sample.dat

# or as a one-liner sans comments:

awk '/RESOURCETAGMAPPINGLIST/ {split($2,a,":"); print a[1],a[3],a[4],a[5]; next} 1' sample.dat

This generates:

arn ec2 us-east-1 XXXXXX
TAGS    app-name    appname1
arn ec2 us-east-1 XXXXXX
TAGS    app-name    appname2
arn ec2 us-east-1 XXXXXX
TAGS    app-name    appname1

CodePudding user response：

Here is one way to do it:

#!/usr/bin/perl
use v5.30; # Perl v5.10 or above is required to use 'say' instead of 'print'
use warnings;

my $file = "datafile.txt"; #declare file name
open( my $fh, "<", $file ) or die( "Can't open `$file`: $!\n" );
#open the file with file handle $fh
while (my $line = <$fh>){ #read the file line by line
    chomp $line;      #remove line breaks
    if ($line =~ m/^RESOURCETAGMAPPINGLIST/){ #if line start with
        my @fields = split(/\t|:/, $line); #split in tab or : characters; each field becomes an element of @fields array
        say (join ' ', (@fields[1,2,3,4])); #join the relevant fields with a single space and print
    }else{
        say $line; #if line does not start with RESOURCETAGMAPPINGLIST, simply print it
    }
}
#when script finishes, Perl will automatically close the input file.

CodePudding user response：

I assume that one keeps the fields 1,3,4,5 from the colon-separated part.

perl -wple'
    s{^RESOURCETAGMAPPINGLIST\s (. )}
     { join " ", ( $1 =~ /([^:] )/g )[0,2..4] }e' file

With -p the variable $_, which has the line to process, is printed after the processing.

So if that keyword isn't matched the $_ remains unchanged. If it is matched it gets replaced with the return of the code in the replacement side. (With /e modifier the replacement side is evaluated as code.)

Or: test for the word, and either split the line and join the needed parts or print it as is

perl -wnlE'say 
    /^RESOURCETAGMAPPINGLIST/ ? join " ", (split /\s |:/)[1,3..5] : $_' file

or first split and then test and print accordingly

perl -wnE'
    @f = split /\s |:/; 
    say $f[0] eq "RESOURCETAGMAPPINGLIST" ? "@f[1,3,4,5]" : "@f"' file

This retains only single spaces (until it is clarified whether it should preserve spaces).

All are broken into lines so that it is easier to read. They can be copy-pasted as they are (in bash), or brought onto one line. Or, this can be written far more nicely in a file, but the question seems to be asking for a command-line program.