1，perl从文件中搜索包含关键字的行。
#!/usr/bin/perl
use strict;
use warnings;
my $log_file = '/home/aaa/log';
open(LOG,"< $log_file") or die "Unable to open logfile:$!\n";
while(){
print if /\[error]|error/;
}
close(LOG);
解释：从文件中打印包含“[error]”或者“error‘关键字的行。
2，perl从文件中找出要匹配的关键字
#!/usr/bin/perl
use strict;
use warnings;
if (scalar(@ARGV) < 2) {
print "Usage: $0\n\n";
exit(1);
}
my $ip = $ARGV[0];
my $iface = $ARGV[1];
# Check if ip is already here
my $ip_check = `/sbin/ip addr show`;
if ($ip_check =~ /$ip/) {
print "OK: IP address is already here\n";
exit(0);
}
# Get physics device
my $ipaddr = `/sbin/ifconfig $iface`;
# Get ethernet address
$ipaddr =~ /HWaddr\s*([0-9A-F\:]+)/i;
my $if_eth = $1;
print "$if_eth\n";
# Get broadcast address and netmask
$ipaddr =~ /Bcast:\s*([\d\.]+)\s*Mask:\s*([\d\.]+)/i;
my $if_bcast = $1;
my $if_mask = $2;
print "$if_bcast\n";
print "$if_mask\n";
print "OK\n";
exit(0);
脚本运行如下：
[root@localhost crontab]# ./find_ip.pl 192.168.1.91 eth0
00:0C:29:7D:EB:12
192.168.1.255
255.255.255.0
OK
3，输出文件的前几行
#!/usr/bin/perl
use strict;
use warnings;
my $filename = '/opt/1.txt';
open FH, "< $filename" or die "can't open $filename ..... ($!)";
my $line = 0;
my %file = map {($line++, $_)};
print $file{0};
print $file{1};
4，输出文件前几行的另外一种方法
#!/usr/bin/perl
use strict;
use warnings;
my $filename = '/opt/1.txt';
tie my @array, 'Tie::File', $filename or die "$!";
my $total = substr($array[0], 0, length($array[0])-1);
my $use = (split(' ', $array[1]))[0];
my $mail_count = (split(' ', $array[1]))[1];
print "$total\n";
print "$use\n";
print "$mail_count\n";
