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Extract n-digits from string in perl


 
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# 1  
Old 09-07-2017
Extract n-digits from string in perl

Hello,

I have a log file with logs such as
Code:
01/05/2017 10:23:41 [ABCD-22357$0]: file.log.38: database error, MODE=SINGLE, LEVEL=critical, STATE: 01170255 (mode main

how can i use perl to extract the 8-digit number below from the string
Code:
01170255

Thanks
# 2  
Old 09-07-2017
I would suggest using split being saved to an array, then display the appropriate field. Perhaps something like this might help:-
Code:
  my $line = "01/05/2017 10:23:41 [ABCD-22357$0]: file.log.38: database error, MODE=SINGLE, LEVEL=critical, STATE: 01170255 (mode main" ;

  my @tmp_array = split (/ /,$line) ;
  print $tmp_array[9] ;


Does that help?
Robin
# 3  
Old 09-07-2017
Code:
line="01/05/2017 10:23:41 [ABCD-22357$0]: file.log.38: database error, MODE=SINGLE, LEVEL=critical, STATE: 01170255 (mode main"

echo "$line" | perl -e 'foreach my $str (split(/ /, <>)) {if (length($str)==8 && $str=~/^\d+$/) {print "$str\n"}; } '

echo "$line" | sed -n -r '/\b([0-9]{1,8})\b/s/.*\b([0-9]{1,8})\b.*/\1/;p;'

echo "$line" | awk 'length==8 && /^[0-9]+$/' RS=" "

for w in $line ; do if [ ${#w} = 8 ] && [ "${w/[^0-9]*}" = "$w" ] ; then { print "$w" ; } ; fi ; done

This User Gave Thanks to rdrtx1 For This Post:
# 4  
Old 09-07-2017
If the 8-digit number is always preceded by the word "STATE:" then you could use regular expressions as well:

Code:
$
$ cat mylog.txt
01/05/2017 10:23:41 [ABCD-22357$0]: file.log.38: database error, MODE=SINGLE, LEVEL=critical, STATE: 01170255 (mode main
$
$ perl -lne 'print $1 if /STATE:\s+(\d+)/' mylog.txt
01170255
$

If it could be preceded by more than word, then specify them all in your regular expression, like so:

Code:
$
$ cat mylog_1.txt
01/05/2017 10:23:41 [ABCD-22357$0]: file.log.38: database error, MODE=SINGLE, LEVEL=critical, STATE: 01170255 (mode main
something else
over here
01/05/2017 10:23:41 [ABCD-22357$0]: file.log.38: database error, MODE=SINGLE, LEVEL=critical, BLAH: 12345678 (mode main
some other stuff
$
$ perl -lne 'print $2 if /(STATE|BLAH):\s+(\d+)/' mylog_1.txt
01170255
12345678
$


Last edited by durden_tyler; 09-07-2017 at 11:43 AM..
# 5  
Old 09-07-2017
Quote:
Originally Posted by rbatte1
I would suggest using split being saved to an array, then display the appropriate field. Perhaps something like this might help:-
Code:
  my $line = "01/05/2017 10:23:41 [ABCD-22357$0]: file.log.38: database error, MODE=SINGLE, LEVEL=critical, STATE: 01170255 (mode main" ;

  my @tmp_array = split (/ /,$line) ;
  print $tmp_array[9] ;


Does that help?
Robin
Thanks Robin, but i'm looking at a situation where the 8-digit number can appear in another position in the string. In that case it will not always be the 9th element of the array.

---------- Post updated at 10:43 AM ---------- Previous update was at 10:28 AM ----------

Quote:
Originally Posted by durden_tyler
If the 8-digit number is always preceded by the word "STATE:" then you could use regular expressions as well:

Code:
$
$ cat mylog.txt
01/05/2017 10:23:41 [ABCD-22357$0]: file.log.38: database error, MODE=SINGLE, LEVEL=critical, STATE: 01170255 (mode main
$
$ perl -lne 'print $1 if /STATE:\s+(\d+)/' mylog.txt
01170255
$

If it could be preceded by more than word, then specify them all in your regular expression, like so:

Code:
$
$ cat mylog_1.txt
01/05/2017 10:23:41 [ABCD-22357$0]: file.log.38: database error, MODE=SINGLE, LEVEL=critical, STATE: 01170255 (mode main
something else
over here
01/05/2017 10:23:41 [ABCD-22357$0]: file.log.38: database error, MODE=SINGLE, LEVEL=critical, BLAH: 12345678 (mode main
some other stuff
$
$ perl -lne 'print $2 if /(STATE|BLAH):\s+(\d+)/' mylog_1.txt
01170255
12345678
$

How can i do this inside a perl script and not on the command line?
# 6  
Old 09-07-2017
The perl code
Code:
print $1 if /STATE:\s+(\d+)/;

works on a line that is in $_.
These 2 Users Gave Thanks to MadeInGermany For This Post:
# 7  
Old 09-07-2017
Quote:
Originally Posted by james2009
...
How can i do this inside a perl script and not on the command line?
In a Perl program, you'd accept the input log file name (if so desired), open it, loop/process through it and then close it.
Here's a short program called "process_log.pl".
Hopefully the inline comments are descriptive enough.

Code:
$
$
$ cat -n mylog_1.txt
     1  01/05/2017 10:23:41 [ABCD-22357$0]: file.log.38: database error, MODE=SINGLE, LEVEL=critical, STATE: 01170255 (mode main
     2  something else
     3  over here
     4  01/05/2017 10:23:41 [ABCD-22357$0]: file.log.38: database error, MODE=SINGLE, LEVEL=critical, BLAH: 12345678 (mode main
     5  some other stuff
$
$
$ cat -n process_log.pl
     1  #!/usr/bin/perl -w
     2  # ------------------------------------------------------------------------------
     3  # Name : process_log.pl
     4  # Desc : A short and quick Perl program to process log files. It performs
     5  #        rudimentary input validation and error handling.
     6  # Usage: perl process_log.pl <log_file>
     7  # ------------------------------------------------------------------------------
     8  use strict;
     9
    10  # Print usage and quit if incorrect number of parameters were passed.
    11  if ($#ARGV != 0) {
    12      print "Usage: perl process_log.pl <log_file>\n";
    13      exit 1;
    14  }
    15
    16  # Set the file name. Hopefully it can be opened!
    17  my $file = $ARGV[0];
    18
    19  # Open file, loop through each line and process, close file
    20  open(FH, "<", $file) or die "Can't open $file: $!";
    21  while (<FH>) {
    22      # Remove the end of line character
    23      chomp;
    24      if (/(STATE|BLAH):\s+(\d+)/) {
    25          print $2, "\n";
    26      }
    27  }
    28  close(FH) or die "Can't close $file: $!";
    29
$
$ # Test with no parameters
$ perl process_log.pl
Usage: perl process_log.pl <log_file>
$
$ # Test with a file name that cannot be found or opened
$ perl process_log.pl does_not_exist.txt
Can't open does_not_exist.txt: No such file or directory at process_log.pl line 20.
$
$ # Test with the correct file
$ perl process_log.pl mylog_1.txt
01170255
12345678
$
$


Last edited by durden_tyler; 09-07-2017 at 08:22 PM..
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