Two handy snippets to help you parse program output.
snippet 1.
findpositions()
pass it an array of needed headers and the header line.
returns an array ref of results. elements are an anonymous array with ('headername', 'startpos', 'endpos')
getfields()
pass it the ref returned from findpositions and the scalar containing the data.
returns a hashref of name=>value for each position.
#!/usr/bin/perl -w
use strict;
######################################################################
+###############
# This script contains two handy functions to assist in the parsing of
+
# program output.
# The nice thing about it is that it is fairly field position agnostic
+ so it won't
# be so fragile. As long as the names are present and don't change it
+will work.
# Even if they are different widths or in different positions.
+
#
# There are two functions.
# findpositions():
# pass it an array of needed headers and the header line.
+
# returns an array ref of results. els are ['headername', 'stpos',
+ 'endpos']
#
# getfields()
# pass it the ref returned from findpositions and the scalar contai
+ning data.
# returns a hashref of name=>value for each position.
+
#
# Caveats:
# These snippets expect that columns NEVER overlap and they are lef
+t justified.
# Trailing whitespace in values is removed.
######################################################################
+###############
sub findpositions(\@$){
my $headar = shift;
my $line = shift;
my @results;
my @errors = ();
my $pos = 1;
for (my $i = 0; $i < @$headar; $i++){
my $header = quotemeta($headar->[$i]);
if ($line=~/$header\s*/g){
push @results, [ $headar->[$i], $pos - 1, pos($line) - ($p
+os - 1) ];
$pos = pos($line);
}else { # Failure
push @errors, "Couldn't find $headar->[$i]\n" if $^W;
}
}
warn @errors if $^W;
return if @errors;
return \@results;
}
sub getfields{
my $aref = shift; # Headers
my $line = shift; # Data
my %res = ();
foreach (@$aref){
$res{$_->[0]} = substr($line,$_->[1],$_->[2]);
$res{$_->[0]} =~s/\s+$//;
}
return \%res;
}
###########################################################
# Sample
# Run netstat
###########################################################
# Headers we are expecting.
my @ACTIVE_INET_HEADERS = (
'Proto',
'Recv-Q',
'Send-Q',
'Local Address',
'Foreign Address',
'State',
'User',
'Inode',
'PID/Program name',
);
my @ACTIVE_UNIX_HEADERS = (
'Proto',
'RefCnt',
'Flags',
'Type',
'State',
'I-Node',
'PID/Program name',
'Path',
);
##################
# Run command
##################
my @output = `netstat -apve`;
die "Couldn't run netstat" unless @output;
my $href; # Headers;
while (my $line = shift @output){
chomp $line;
###########################################################
# Parse Internet sockets.
###########################################################
if (!$href && $line=~/^Active Internet connections/ ){
print "Active Internet connections.\n","#" x 30,"\n";
$line = shift @output;
if ( $line=~/^Proto/ ){
$href = findpositions(@ACTIVE_INET_HEADERS,$line);
die "Couldn't parse headers!" unless $href;
next;
}else{
die "Unexpected: $line";
}
}
###########################################################
# Parse Unix sockets.
###########################################################
if ($line=~/^Active UNIX domain sockets/ ){
print "\nActive UNIX sockets.\n","#" x 30,"\n";
$line = shift @output;
# Parse Internet sockets.
if ( $line=~/^Proto/ ){
$href = findpositions(@ACTIVE_UNIX_HEADERS,$line);
die "Couldn't parse headers!" unless $href;
next;
}else{
die "Unexpected: $line";
}
}
if ($href){
my $lhref = getfields($href,$line); # Hash with name=>value
##################################################################
+###############
# Why doesn't the line below get flattened? It only prints the fir
+st list.
# print ( map{"\t$_ =\> $lhref->{$_}\n"} sort keys %$lhref) , "#"
+ x 40, "\n" ; # Why bad?
# Anybody? Bueller... Bueller? I suppose two print statements woul
+dn't kill me.
##################################################################
+###############
print map{"\t$_ =\> $lhref->{$_}\n"} sort keys %$lhref;
print "#" x 40, "\n";
}
}
print "Done!\n";
__END__
>netstat -apve sample data
Active Internet connections (servers and established)
Proto Recv-Q Send-Q Local Address Foreign Address St
+ate User Inode PID/Program name
tcp 0 0 somedomainher.net:www trder102.stare.ya:46312 TI
+ME_WAIT user 0 -
tcp 0 0 somedomainher.ne:tproxy trder104.stare.ya:25013 TI
+ME_WAIT user 0 -
tcp 0 0 somedomainher.net:www trder104.stare.ya:49319 TI
+ME_WAIT user 0 -
tcp 0 0 somedomainher.net:www trder104.stare.ya:28205 TI
+ME_WAIT user 0 -
tcp 0 0 somedomainher.net:www trder104.stare.ya:28202 TI
+ME_WAIT user 0 -
tcp 0 0 *:www *:* LI
+STEN user 1957270 16874/httpd
tcp 0 424 somedomainher.net:ssh 209.X.XXX.XXX:1115 ES
+TABLISHED user 1582988 947/sshd2
tcp 0 0 somedomains:netbios-ssn 209.6.XXX.XXX:1026 ES
+TABLISHED user 1582180 892/smbd
tcp 0 0 *:https *:* LI
+STEN user 714 607/httpd
tcp 0 0 *:mysql *:* LI
+STEN user 654 594/mysqld
tcp 0 0 *:ssh *:* LI
+STEN user 576 540/sshd2
tcp 0 0 *:locker *:* LI
+STEN autobot 560 536/SERVER
tcp 0 0 *:tproxy *:* LI
+STEN autobot 546 530/ShipTax S
tcp 0 0 *:netbios-ssn *:* LI
+STEN user 456 482/
tcp 0 0 *:616 *:* LI
+STEN user 400 433/
tcp 0 0 *:npmp-gui *:* LI
+STEN user 392 433/
udp 0 0 *:sunrpc *:*
+ user 274 330/
raw 208 0 *:icmp *:* 7
+ user 2017587 -
raw 0 0 *:icmp *:* 7
+ user 0 -
raw 0 0 *:tcp *:* 7
+ user 0 -
Active UNIX domain sockets (servers and established)
Proto RefCnt Flags Type State I-Node PID/Program n
+ame Path
unix 1 [ ] STREAM CONNECTED 2021255 16879/httpd
+ @000044ac
unix 1 [ ] STREAM CONNECTED 2011633 16877/httpd
+ @00004466
unix 1 [ ] STREAM CONNECTED 1969869 16883/httpd
+ @00004325
unix 1 [ ] STREAM CONNECTED 1965032 16875/httpd
+ @00004307
unix 1 [ ] STREAM CONNECTED 2021003 16878/httpd
+ @000044ab
