Here is a quick question by one of our regular reader :
How to write a perl script that can monitor my disk space under UNIX or Linux and send me an email alert?
There is a nice perl system routine called Perl df or Filesys::DiskSpace. This routine displays information on a file system such as its type, the amount of disk space occupied, the total disk space and the number of inodes etc.
Task: Install Filesys::DiskSpace
First you need to install this perl module using apt-get or from cpan (Comprehensive Perl Archive Network).
$ sudo apt-get install libfilesys-diskspace-perl
Perl script code to monitor disk space
Now write a perl script called df.pl:
$ vi df.pl
Append following code:
#!/usr/bin/perl use strict; use warnings; use Filesys::DiskSpace; # file system /home or /dev/sda5 my $dir = "/home"; # get data for /home fs my ($fs_type, $fs_desc, $used, $avail, $fused, $favail) = df $dir; # calculate free space in % my $df_free = (($avail) / ($avail+$used)) * 100.0; # display message my $out = sprintf("Disk space on $dir == %0.2f\n",$df_free); print $out; |
Save and close the file. Run this script as follows:
$ chmod +x df.pl
$ ./df.pl
Output:
Disk space on /home == 75.35
So /home has 75.35% free disk space. Next logical step is to compare this number to limit so that you can send an email if only 10% free disk space is left on /home file system. Here is the code with
#!/usr/bin/perl use strict; use warnings; use Filesys::DiskSpace; my $dir = "/home"; # warning level 10% my $warning_level=10; my ($fs_type, $fs_desc, $used, $avail, $fused, $favail) = df $dir; my $df_free = (($avail) / ($avail+$used)) * 100.0; # compare free disk space with warning level if ($df_free < $warning_level) { my $out = sprintf("Send an Email - Disk space on $dir => %0.2f%% (WARNING Low Disk Space)\n",$df_free); print $out; } else { my $out = sprintf("Disk space on $dir => %0.2f%% (OK)\n",$df_free); print $out; } |
Run script as follows:
$ ./df.pl
Output:
Send an Email - Disk space on /home => 3.99% (WARNING Low Disk Space)
Here is final code that send an email alert ( download):
#!/usr/bin/perl # Available under BSD License. See url for more info: # http://www.cyberciti.biz/tips/howto-write-perl-script-to-monitor-disk-space.html use strict; use warnings; use Filesys::DiskSpace; # file system to monitor my $dir = "/home"; # warning level my $warning_level=10; # email setup my $to='admin@yourdomain.com'; my $from='webmaster@YOURDOMAIN.COM'; my $subject='Low Disk Space'; # get df my ($fs_type, $fs_desc, $used, $avail, $fused, $favail) = df $dir; # calculate my $df_free = (($avail) / ($avail+$used)) * 100.0; # compare if ($df_free < $warning_level) { my $out = sprintf("WARNING Low Disk Space on $dir : %0.2f%% ()\n",$df_free); # send email using UNIX/Linux sendmail open(MAIL, "|/usr/sbin/sendmail -t"); ## Mail Header print MAIL "To: $to\\n"; print MAIL "From: $from\\n"; print MAIL "Subject: $subject\\n"; ## Mail Body print MAIL $out; close(MAIL); } |
You can run this script as a cron job:
@hourly /path/to/df.pl
Recommended readings
=> Read man page of this module by typing following command:
$ man filesys::diskspace
=> CPAN filesys::diskspace webpage
=> Sending mail with Perl mail script and How do I send html email from Perl?
36 comment
Nice script.
I though had to change the sendmail part to:
## Mail Header
print MAIL “To: $tonâ€;
print MAIL “From: $fromnâ€;
print MAIL “Subject: $subjectnâ€;
to get sendmail working correctly.
Thomas,
Opps stupid xhtml was causing problem. Post has been updated
Appreciate your post.
No prb. Nothing beats a good script ;ø)
You could also you Monit [1] to monitor disk space and several other services/daemons.
[1] http://www.tildeslash.com/monit/
IMHO, it would be better to implement a server monitoring system, which will also allow monitoring of other metrics, such as CPU utilisation, memory use, network port counts, log messages, network traffic, network checks, and more.
I use hobbit for this, which supports all of this out-the-box, and with no configuration required to have the memory, cpu utilisation, disk usage graphs working.
Although your perl script is nice, you could do it with a standard shell script as well:
@Markus / Buchan
I do agree with all of you monit is much better but one of our loyal and regular reader wanted perl script.
@Pete
Thanks for a shell script.
Appreciate all of your posts.
hi, can you please help me to write a perl script to read emails?
I am installing the Filesys::diskspace module and when I do make test I get the error as
———————————————-
t/linux-ext2…..Can’t use an undefined variable as ARRAY reference at t/linux-ext2.t line26
——————————————–
Anyone has encountered this problem previously..can you please tell me what the problem is
I get this error
“Cannot use df on this machine (untested or unsupported). ”
everything installed (moudles etc..)
can some one help me?
thank you!
I get “statfs failed on /home (new filesystem type?) .. ” error. Any idea?
Thanks!
I am getting an error “An error occured. statvfs failed. Did you run h2ph?” Any idea?
How we can make tests that we don’t send multiple e-mails? I’ve done that in shell scripts by setting up /tmp/mail_sent file and checking if it exists. After I logged onto a machine and free up some disk, I would remove the lock file.
My Perl is a bit rusty, so can anyone write the enhancement?
Well, for multiple e-mails, here it is:
## Mail Body
if (-e "/tmp/sms_sent")
{
print "already sent";
}
else
{
print MAIL $out;
system ("touch /tmp/sms_sent");
}
Hi!
I tried running the script on my mac os x leopard 10.5.3 machine and it says “Cannot use df on this machine (untested or unsupported).”
What should I do? Sorry I’m quite a newbie into this thing.
For RPM based Linux systems like CentOS and Fedora, install the perl-Filesys-DiskSpace package with:
# yum install perl-Filesys-DiskSpace
Hi
I am a newbie to perl programming. Can somebody explain the following line? I understood rest of the program except for this bit. How are we getting this array out of the df command?
my ($fs_type, $fs_desc, $used, $avail, $fused, $favail) = df $dir;
Thanks for your help!
Hi RC,
I have just basic knowledge of UNIX Cmd and now want to write Unix PErl Script.
.which book I can refer to go with.
Thanks,
the df command there is part of the perl library FileSys::DiskSpace and not the normal df command available from the OS. This script is short and sweet but in my opinion, overly dependant on external libraries. The whole thing could have been written thusly..
Guys, my script is slightly different, basically i’m wanna count files in a directory and after certain amount of files, the script should send me alert.
I’ve two problems with the current.
1. I’m recieving emails but without body message
2. I’m getting following error while execute this script:
Useless use of private variable in void context at ./VMCount.pl line 38.
However there is nothing wrong with line# 38, as i hve “}” on this line
any comments?
Hello,
would enyone tell me why do I get such an error during execution of Kens script:
—————————————–
Use of uninitialized value in concatenation (.) or string at ./new_df.pl line 17.
tail: cannot open `+2′ for reading: No such file or directory
Use of uninitialized value in addition (+) at ./new_df.pl line 20.
Use of uninitialized value in addition (+) at ./new_df.pl line 20.
Use of uninitialized value in division (/) at ./new_df.pl line 20.
Illegal division by zero at ./new_df.pl line 20.
——————————————
It happens also during execution of original script from article above:
——————————————
Illegal division by zero at ./df.pl line 26.
——————————————
both errors are about the same line:
my $df_free = (($avail) / ($avail+$used)) * 100.0;
I have perl-Filesys-DiskSpace installed in my system.
I do not understand what it is complaining about
Any ideas?
Dear Peter,
> Although your perl script is nice, you could do it with a standard shell script as well:
for fs in `df -k|awk ‘{print $1}’|sed -n “2,14 p”`; do
x=”`df -kl | grep $fs | awk ‘{ print $5 }’| sed -e ‘s/%//’`”
…
done
Why do You use pipe snakes, like df -k|awk ‘{print $1}’|sed -n “2,14 p” and df -kl | grep $fs | awk ‘{ print $5 }’| sed -e ‘s/%//’??? If You start awk why do You need a grep and sed? On the other hand if You have n disks You call df (n+1) times instead of once.
Good byte!
HI
I am newnie in perl programming..
I am getting this error “An error occured. statvfs failed. Did you run h2ph?”
Could anyone help what is this error mean? and how to solve it?
Thanks
Hi ,
I am a newbie in perl….can any body tell how to use the same script when i am using windows -XP?
Thanks in advance
sorry I’m new in hardware programing.
can I use vb6 / .net programing to monitor disk space and send an email under Linux ?
Hi All,
I am very new to Unix. Just got a new assignment where I need to write Unix Perl Script.
Can some one segues me which book can help to know Perl script for beginner.
Please help..with link also.
Thanks
I got this on CentOS 5.5 64-bit:
./df.pl
Illegal division by zero at ./df.pl line 23.
Cant get this script to run. Can anyone help?
running on Solaris 10
Makefile.PL and make complete successfully
make test spits out errors
# make test
PERL_DL_NONLAZY=1 /usr/bin/perl “-MExtUtils::Command::MM” “-e” “test_harness(0, ‘blib/lib’, ‘blib/arch’)” t/*.t
t/1st…………ok
t/freebsd-ufs….skipped
all skipped: no reason given
t/linux-ext2…..skipped
all skipped: no reason given
t/linux-vfat…..skipped
all skipped: no reason given
t/solaris-ufs….An error occured. statvfs failed. Did you run h2ph?
FAILED before any test output arrived
Failed Test Stat Wstat Total Fail Failed List of Failed
—————————————————————–
t/solaris-ufs.t ?? ?? % ??
3 tests skipped.
Failed 1/5 test scripts, 80.00% okay. 8/9 subtests failed, 11.11% okay.
*** Error code 29
make: Fatal error: Command failed for target `test_dynamic’
running h2ph hangs after ‘redefine’ message
# h2ph -r -l
require ‘_h2ph_pre.ph’;
no warnings ‘redefine’; // hangs here
I added require ‘_h2ph_pre.ph’; to the h2ph and re-ran with the same result.
What’s up with this?
Solaris 10
resolved using different arguments:
h2ph * sys/*
Thanks for the script. I tweaked it so that it would monitor multiple folders. I also added a “–test” command line option to send out a test email. Here it is:
#!/usr/bin/perl # Available under BSD License. See url for more info: # http://www.cyberciti.biz/tips/howto-write-perl-script-to-monitor-disk-space.html # Pass in command line parameter "--test" to perform an email test. use strict; use warnings; use Filesys::DiskSpace; # --------------------------- # Configuration section # --------------------------- # default warning level my $default_warning_level=10; # email setup my $to='admin@yourdomain.com'; my $from='webmaster@YOURDOMAIN.COM'; my $subject='Low Disk Space'; # folders to check sub perform_checks { &check_free_space("/", 30); &check_free_space("/mnt/data"); &check_free_space("/mnt/storage"); &check_free_space("/mnt/backup", 20); } # --------------------------- # Main script # --------------------------- my $out = ""; # Check free space for folder and add to email message if it is below warning level. # Parameters: # folder_to_check - The path of the filesystem to check. # warning_level - If the free disk space percentage is below this level, # an email is sent. If this parameter is omitted, the # default level will be used. sub check_free_space { my ($dir, $warning_level) = @_; # set warning level to default if not specified if(!defined($warning_level)) { $warning_level = $default_warning_level; } # get df my ($fs_type, $fs_desc, $used, $avail, $fused, $favail) = df $dir; # calculate my $df_free = ($avail / ($avail + $used)) * 100.0; # compare if (($df_free < $warning_level) || (defined($ARGV[0]) && ($ARGV[0] eq "--test"))) { # append to email $out .= sprintf("WARNING Low Disk Space on $dir : %0.2f%% ()n",$df_free); } } &perform_checks; # check if there are warnings to email if($out ne "") { # send email using UNIX/Linux sendmail open(MAIL, "|/usr/sbin/sendmail -t"); ## Mail Header print MAIL "To: $ton"; print MAIL "From: $fromn"; print MAIL "Subject: $subjectn"; ## Mail Body print MAIL $out; } close(MAIL);I am getting this issue on 64-bit RHEL and CentOS:
Illegal division by zero at ./df.pl line 23.
Line 23 is
my $df_free = (($avail) / ($avail+$used)) * 100.0;
Try this works for me:
my ($fs_type, $fs_desc, $used, $avail, $fused, $favail) = split(” “, `df -PT $dir | tail -n +2`);
Very much thanks for this nice script. I will use it for my homework.
i want to concatenate $_ and $var in to $new in perl ,but it is not concatenating why?
$new = “$_”.”/$var”;
@arr1= `ls -a $new`;
Any Tutorials for perl scripting.. I would need a perl script to find cpu utilization on a solaris host.
Thanks Arun
This checks all volumes on the system, and sends out a warning vs critical notice.
#!/usr/bin/perl -w # check_disk_space.pl # Send an email notice out when mounted file systems are past a given percentage. # # Perl v5.8.8 # Tested under RHEL4, RHEL5, and RHEL6 # # When this script is run it will check the status of all mounted file systems # using the df command and if the percentage is past the given critical set level # will send out an email notice every time it is run. A set warning percentage # only send out an email every number_of_days_before_next_warning. # It keeps track of the number_of_days_before_next_warning using lock files. # # The check_disk_space.xml config file should be in the same directory as the program, # and be given the same name if the program name is changed. # #check_disk_space.xml # < = #- # # 90 # 99 # 7 # /home// # yes # no # /bin/df # /bin/find # /bin/rm # /bin/date # /bin/hostname # /usr/sbin/sendmail # user@mail.com # Disk Check <user@system.com> # Disk Check # # Disk Check # #- # # The following config toggles whether the host appears in the subject line. # A value of "yes" will trigger the hostname include. # no # # The following line troggles weather or not lock files are created with a # hidden dot prefix. A value of "yes" will trigger the hidden file. # yes # # The following line determins where the lock files will be placed. If left # blank the lock files will be saved in the current directory. Be sure to # end a directory path with a "/" in the config file. #/home// # # This program doesn't require any special privlege accesses, except read/write # access to the lockfile directory. # # Recommended Crontab Entry: # # Check precentage of disk used every day and send out a email if critical levels are reached. # 0 7 * * * cd /home//bin; /home//bin/check_disk_space.pl # # Script requirements: install XML Simple # yum install perl-XML-Simple # # History: # --------------------------------------------------------------------------- # 2014-02-24 kienenbe Started, works. # use XML::Simple; use File::Basename; #use Data::Dumper; #>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>> # Get the mount points from the df command. #>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>> sub get_filesystem_data { my @mount_points; my $df_line; my $filesystem; my $junk; my $total_size; my $amount_used; my $amount_avalible; my $percent_used; my @df_output = `$command_df -lh`; foreach $df_line (@df_output) { if ($df_line =~ m#d%#) { #print "->$df_line"; # Break out the needed data. ($percent_used,$filesystem) = split(/% /, $df_line); chomp $filesystem; ($junk,$total_size,$amount_used,$amount_avalible,$percent_used) = split(/s+/, $percent_used); # Record the data for the filesystem mount point. $filesystem_info{"$filesystem"}{"total_size"} = "$total_size"; $filesystem_info{"$filesystem"}{"amount_used"} = "$amount_used"; $filesystem_info{"$filesystem"}{"amount_avalible"} = "$amount_avalible"; $filesystem_info{"$filesystem"}{"percent_used"} = "$percent_used"; } } } #>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>> # Format the text report output for display. #>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>> # system.mysystem.org # Fri Feb 21 13:47:03 UTC 2014 # # ---- Critical file system space at or above 45% ---- # # Size Used Avail Use% Mounted on # 1.8T 769G 973G 45% /mnt/backup # 1.1T 436G 550G 45% /data # # ---- Warning file system space at or above 8% ---- # # Size Used Avail Use% Mounted on # 485M 38M 422M 9% /boot sub format_report_output { $warning_duplicate_check = 0; $critical_duplicate_check = 0; my $filename; # Cycle though each filesystem mount point. foreach my $filesystem (keys %filesystem_info) { if ($filesystem_info{"$filesystem"}{"percent_used"} >= $critical_percent_used) { if ($critical_duplicate_check eq 0) { # Only print the date and time stamp if this is the first warning check. if ($warning_duplicate_check eq 0) { $formated_report .= "n $Hostnamen $TimeStampn"; } $formated_report .= "n ---- Critical file system space at or above ${critical_percent_used}% ----nn"; $formated_report .= sprintf(" %5s %5s %5s %5s %-60sn", "Size","Used","Avail","Use%","Mounted on"); $critical_duplicate_check = 1; } $formated_report .= sprintf(" %5s %5s %5s %5s %-60sn", $filesystem_info{$filesystem}{total_size},$filesystem_info{$filesystem}{amount_used},$filesystem_info{$filesystem}{amount_avalible},"$filesystem_info{$filesystem}{percent_used}%",$filesystem); } elsif ($filesystem_info{"$filesystem"}{"percent_used"} >= $warning_percent_used) { # Concert the file system mount point to a file name. $filename = &convert_filesystem_path_to_name($filesystem); # Remove warning locks for file system mount points past the number_of_days_before_next_warning &remove_warning_lockfile($filename); if (&check_for_warning_lockfile($filename)) { # Do nothing } else { if ($warning_duplicate_check eq 0) { # Only print the date and time stamp if this is the first critical check. if ($critical_duplicate_check eq 0) { $formated_report .= "n $Hostnamen $TimeStampn"; } $formated_report .= "n ---- Warning file system space at or above ${warning_percent_used}% ----nn"; $formated_report .= sprintf(" %5s %5s %5s %5s %-60sn", "Size","Used","Avail","Use%","Mounted on"); $warning_duplicate_check = 1; } $formated_report .= sprintf(" %5s %5s %5s %5s %-60sn", $filesystem_info{$filesystem}{total_size},$filesystem_info{$filesystem}{amount_used},$filesystem_info{$filesystem}{amount_avalible},"$filesystem_info{$filesystem}{percent_used}%",$filesystem); # Create a warning lock file for the current file system mount point. &write_warning_lockfile($filename); } } } } #>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>> # Send out the email to the recipients. #>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>> sub send_email_notice { # Send full report to recepiants(s) # Remove complaint about global empty vars such as ${mail_subject_postfix} no warnings 'uninitialized'; if ( $warning_duplicate_check eq 1 or $critical_duplicate_check eq 1) { open (MAIL, "|$command_sendmail -t") || die "Can't open the mail binary: ${command_sendmail}!n"; print MAIL "X-Mailer: ${mail_x_mailer}n"; print MAIL "Return-Path: root@${Hostname}n"; print MAIL "From: ${mail_from} n"; print MAIL "To: ${mail_to}n"; if ($Include_Hostname_In_Subject eq "yes") { print MAIL "Subject: ${mail_subject_prefix}${Hostname}${mail_subject_postfix}nn"; } else { print MAIL "Subject: ${mail_subject_prefix}${mail_subject_postfix}nn"; } print MAIL "n${formated_report}nn"; close (MAIL); } } #>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>> # Conver the file system mount point to a lockfile name. #>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>> sub convert_filesystem_path_to_name { my $filesystem_path = shift; my $lockfile_name; $filesystem_path =~ s#/#_#g; $filesystem_path =~ s# #_#g; if ($hide_warning_lockfile eq "yes") { $lockfile_name = "." . $program_name . "_warning_lock" . $filesystem_path; } else { $lockfile_name = $program_name . "_warning_lock" . $filesystem_path; } return ($lockfile_name); } #>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>> # Save the warning lockfile #>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>> # Creates the locking file in the format of: # / are converted to underscores for mount point. # # # -rwxr-x---. 1 user user 9211 Feb 21 13:46 df.pl* # -rw-rw-r--. 1 user user 0 Feb 21 13:47 .df_warning_lock_boot sub write_warning_lockfile { my $lockfile_name = shift; my $lockfile_directory = "./"; # Check if the $warning_lock_directory has been set. # If so use it instead of the current directory. if ( $warning_lock_directory) { $lockfile_directory = $warning_lock_directory; } # Check for the warning lockfile. # If it already exists exit. if ( -e "${lockfile_directory}${lockfile_name}" ) { return; } open (WARNING_LOCKFILE, '>', ${lockfile_directory}.${lockfile_name}) or $formated_report .= "nUnable to save warning lockfile for ${lockfile_directory}${lockfile_name}n Warnings will be sent out every time the script runs.nn"; close (WARNING_LOCKFILE); } #>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>> # Check for the warning lockfile #>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>> sub check_for_warning_lockfile { my $lockfile_name = shift; my $lockfile_directory = "./"; # Check if the $warning_lock_directory has been set. # If so use it instead of the current directory. if ( $warning_lock_directory) { $lockfile_directory = $warning_lock_directory; } # Check for the warning lockfile. if ( -e "${lockfile_directory}${lockfile_name}" ) { return 1; } else { return 0; } } #>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>> # Remove the warning lockfile #>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>> sub remove_warning_lockfile { my $lockfile_name = shift; my $lockfile_directory = "./"; # Check if the $warning_lock_directory has been set. # If so use it instead of the current directory. if ( $warning_lock_directory) { $lockfile_directory = $warning_lock_directory; } # If the file doesn't exist just exit. if (! -e "${lockfile_directory}${lockfile_name}" ) { return; } # Remove the warning lockfile. `$command_find ${lockfile_directory}${lockfile_name} -mtime +${number_of_days_before_next_warning} -type f -exec $command_rm -f {} \;`; } # Run the main routine. &Start; #>>>>>>>>>>>>> #> Main Start #>>>>>>>>>>>>> sub Start { #declare all major variables used in this subroutine. local (%filesystem_info, $TimeStamp, $Hostname, $formated_report, $warning_duplicate_check, $critical_duplicate_check, $program_name); # Obtain configuration from a file with a name inferred from this # script's name. ($program_name) = split(/./, basename($0)); my $program_full_name =basename($0); # if you don not wish to use XML::Simple comment out next line.. $config = XMLin("${program_name}.xml", SuppressEmpty => 'undef'); # if you don not wish to use XML::Simple configure variable directly here. # if you don't use the XML config file you must place a "" in front of the # "@" in your email address so it is not interpreted as an array variable. # ex: local $mail_to = "vadapt.notice@gmail.com"; local $command_date = $config->{'command_date'}; local $command_df = $config->{'command_df'}; local $command_find = $config->{'command_find'}; local $command_hostname = $config->{'command_hostname'}; local $command_rm = $config->{'command_rm'}; local $command_sendmail = $config->{'command_sendmail'}; local $warning_percent_used = $config->{'warning_percent_used'}; local $critical_percent_used = $config->{'critical_percent_used'}; local $number_of_days_before_next_warning = $config->{'number_of_days_before_next_warning'}; local $warning_lock_directory = $config->{'warning_lock_directory'}; local $hide_warning_lockfile = $config->{'hide_warning_lockfile'}; local $Include_Hostname_In_Subject = $config->{'Include_Hostname_In_Subject'}; local $mail_to = $config->{'mail_to'}; local $mail_from = $config->{'mail_from'}; local $mail_subject_prefix = $config->{'mail_subject_prefix'}; local $mail_subject_postfix = $config->{'mail_subject_postfix'}; local $mail_x_mailer = $config->{'mail_x_mailer'}; # Get the hostname local $Hostname = `$command_hostname -f`; chomp $Hostname; # Get the date timestamp $TimeStamp = `$command_date`; chomp $TimeStamp; # Do the work &get_filesystem_data; &format_report_output; &send_email_notice; # uncomment to print report when run. #print $formated_report; #End the program exit; }