How to assign a password present in a file to a variable ?

Let's say you have a file 'secretfile' which contains the password 'newpass'. You want to assign the password mentioned in that file to a variable called 'pass1'.  The syntax will go like this:

# cat  secretfile
newpass

Method 1
# pass1=$(cat secretfile)
# echo $pass1
newpass

Method 2
# read pass1 < secretfile
# echo $pass1
newpass

Setting alias for 'ls -l' command

I wish to enhance the default alias ('ll') for 'ls -l' command into more pleasing one:

Following is the alias options which I set for 'll' :   # alias ll='ls -lhGpt --color=always'
'-h' - Human readable
'G' - No Group information
'p' - Append / notation for folders
't' - Sort by modification time.

SAMPLE OUTPUT:

[ashok@hostxyz etc]$ ll
total 3.5M
-rw-r--r--  1 root 204K May 20 04:05 prelink.cache
-rw-r--r--  1 root  14K May 16 20:36 group
-r--------  1 root 7.6K May 16 20:36 gshadow
-rw-r--r--  1 root  43K May 16 20:36 passwd
-r--------  1 root  27K May 16 20:36 shadow
-rw-r--r--  1 root  14K May 16 20:33 group-
-r--------  1 root 7.6K May 16 20:33 gshadow-
-rw-r--r--  1 root  43K May 16 20:33 passwd-
-r--------  1 root  27K May 16 20:33 shadow-
drwxr-xr-x  2 root 4.0K May  9 05:16 ssh/
drwxr-xr-x  2 root 4.0K May  8 19:00 blkid/
drwxr-xr-x 10 root 4.0K May  8 06:11 sysconfig/
-rw-r--r--  1 root  128 May  7 03:55 resolv.conf

.

.

<Output truncated>

Syntax to check NIC statistics using 'sar' command

This syntax checks the statistics of 'eth1' interface:
[root@hostxyz ~]# sar -n DEV -f /var/log/sa/sa15 -s 18:00:01 -e 23:01:01 | head -3 | tail -1 | sed 's/^.........../           /'; sar -n DEV -f /var/log/sa/sa15 -s 18:00:01 -e 23:01:01 | grep "eth1"
                      IFACE   rxpck/s   txpck/s   rxbyt/s   txbyt/s   rxcmp/s   txcmp/s  rxmcst/s
06:10:01 PM      eth1     20.54      0.02   2056.62      3.12      0.00      0.00      0.00
06:20:01 PM      eth1     26.11      0.01   2650.42      1.98      0.00      0.00      0.00
06:30:01 PM      eth1     17.03      0.01   1711.49      1.98      0.00      0.00      0.00
06:40:01 PM      eth1     10.40      0.01    972.02      1.60      0.00      0.00      0.00
06:50:01 PM      eth1     24.11      0.02   2426.33      2.74      0.00      0.00      0.00
07:00:01 PM      eth1     25.27      0.01   2554.85      1.87      0.00      0.00      0.00
07:10:01 PM      eth1     13.36      0.01   1312.31      1.98      0.00      0.00      0.00
07:20:01 PM      eth1     12.21      0.02   1175.69      3.12      0.00      0.00      0.00
07:30:01 PM      eth1     25.09      0.01   2566.25      1.98      0.00      0.00      0.00
07:40:01 PM      eth1     26.01      0.01   2612.24      1.60      0.00      0.00      0.00
07:50:01 PM      eth1    206.35    635.89  13526.21 947854.38      0.00      0.00      0.00
08:00:01 PM      eth1   1326.80   4410.98  80781.99 6673444.08      0.00      0.00      0.00
08:10:01 PM      eth1    796.86   2608.67  49050.73 3947034.38      0.00      0.00      0.00
08:20:01 PM      eth1    773.95   2411.76  47858.10 3649035.90      0.00      0.00      0.00
08:30:01 PM      eth1    798.65   2814.04  48448.94 4257857.47      0.00      0.00      0.00
08:40:01 PM      eth1 599122.53 1729538.33 3278958.93 585797.40      0.00      0.00      0.00
08:50:01 PM      eth1   1126.42   3821.02  68802.91 5781612.42      0.00      0.00      0.00
09:00:01 PM      eth1   1416.86   4984.36  85843.95 377147.69      0.00      0.00      0.00
09:10:01 PM      eth1    803.29   2777.80  48717.98 4202947.25      0.00      0.00      0.00
09:20:01 PM      eth1    129.55    352.83   8700.49 533737.74      0.00      0.00      0.00
09:30:01 PM      eth1     25.34      0.01   2581.83      1.98      0.00      0.00      0.00
09:40:01 PM      eth1     15.67      0.01   1523.95      1.79      0.00      0.00      0.00
09:50:01 PM      eth1     11.38      0.01   1066.06      1.60      0.00      0.00      0.00
10:00:01 PM      eth1     23.75      0.03   2366.47      3.01      0.00      0.00      0.00
10:10:01 PM      eth1     26.29      0.01   2679.49      1.98      0.00      0.00      0.00
10:20:01 PM      eth1     12.79      0.01   1241.40      1.98      0.00      0.00      0.00
10:30:01 PM      eth1     13.03      0.03   1273.22      3.12      0.00      0.00      0.00
10:40:01 PM      eth1     25.71      0.01   2586.43      1.60      0.00      0.00      0.00
10:50:01 PM      eth1     24.44      0.01   2448.89      1.60      0.00      0.00      0.00
11:00:01 PM      eth1     10.38      0.01    958.51      1.87      0.00      0.00      0.00
Average:         eth1    288.58    929.73  18156.03 212554.92      0.00      0.00      0.00
[root@hostxyz ~]#

Perl subroutine to check Database Status

sub CheckDBStatus($)
{
my $host = $_[0];
my $dbStatus=`ssh $host -C "ps -ef | grep ora_pmon | grep -v grep -c"`;
if ($dbStatus == 1)
{
Log("Database is up on $host",0,LOGFILE);
return("0");
}
else
{
Log("Database is down on $host",0,LOGFILE);
return("1");
}
}

Note: You can use appropriate string to capture Oracle process with grep command.

Perl subroutine to un-mount a file-system

sub UnMountVolume($)
{
  my $mountPoint = $_[0];
  print "Un-mounting $mountPoint\n";
  # Checking if the mount point exists
  if ( grep m{$mountPoint}, qx{/bin/mount} )
  {
    #Mount point exists, attempt to unmount it without force option
    system("/bin/umount $mountPoint");
  }
  else
  {
    print "$mountPoint is not mounted, please check it out\n";
  }
}

Zip files using 'find' command

Let's say we want to Zip files which are more than a week time under a folder /var/log/nmon :

# for i in `find /var/log/nmon -mtime +7 -type f -print`; do gzip $i; done

Command-line syntax to reset the password

Let’s say we have to reset the Root password of a Linux machine to “XYZabc123”.  We can use the below command set to do it. This can be executed on remote machines if we have a centralized administration server.

# echo ‘XYZabc123’ > /opt/pass; passwd --stdin root < /opt/pass; rm -f  /opt/pass

Perl script to list all Failed Login attempts in Linux

#!/usr/bin/perl -w
# Description             :  Upon execution, this script will list all the Failed Login attempts on a Linux Server
# Mode of Execution  :  As 'root' user from shell prompt
# Developed by          :  Ashok Raj
# Version                   :  1.2
# -------------------------------------------------------------------------------------------------------------------------

$osnam=`uname -s`;
chomp($osnam);
$cnt=0;

if($osnam eq 'Linux')
{
chdir "/var/log" or die "$!";
@arylog = `cat ./secure*|grep 'Failed password'`;
print "\n";
print "REPORT ON FAILED ATTEMPT LOGINS\n\n";
print " DATE/TIME       USERNAME\tHOSTNAME/IPADDRESS\n";
print "---------------------------------------------\n";
foreach(@arylog)
 {
 if($_ =~ m/(\w+\s+\d+\s\d\d:\d\d:\d\d)\s\S+\ssshd\[\d+\]:\s+Failed\s.*?\sfor.*?\s(\w+)\sfrom\s+(\S+)/)
            {
              printf "%-16s   %-16s%-16s\n",$1,$2,$3;
              $cnt++;
            }
}
}
print "\nTotal Number of Failed Attempts: $cnt \n\n";