amit - Amit's Blog (Page 5)

Shell script to display recipient email from message id - postfix

#!/bin/bash if [ -z "$1" ];then echo "Usage:$0 <message id="">" else abuse=`echo $1| cut -f2 -d.

ftp access to files outside base directory

It is possible to grant ftp access to files outside the home directory of the user. #vi /etc/vsftpd/vsftpd.conf **Uncomment or add the following : ** chroot_local_user=YES Now create a directory to mount the folder to users home directory which you want to grant access to: mkdir

Zabbix Installation guide

Zabbix Server Create user and groups for zabbix groupadd -g 130 zabbix useradd -u 130 -g zabbix -c 'Zabbix monitoring' zabbix``` **Install Dependencies:** `yum install zlib-devel mysql-devel glibc-devel curl-devel gcc automake mysql libidn-devel openssl-devel net-snmp-devel rpm-devel OpenIPMI-devel` For Centos 5: rpm -Uvh

Installing and configuring lighttpd with php support

Download the latest source from lighttpd.net $wget -O http://download.lighttpd.net/lighttpd/releases-1.4.x/lighttpd-1.4.29.tar.gz /usr/src/lighttpd.tar.gz $cd /usr/src $tar -zxvf lighttpd.tar.gz

php tips and tricks

Php Tweaks, settings and tricks Php Set display Error for a specific page: To display errors for a specific page, set this on the top of the php page: ini_set(‘display_errors’, 1); ini_set(‘log_errors’, 1); ini_set(‘error_log’, dirname(FILE) . ‘/error_log.txt’); error_reporting(

Zabbix Tutorials

Zabbix Monitor Postfix queue: UserParameter=postfix.queue,postqueue -p | find /var/spool/postfix/{deferred,active,maildrop}/ -type f | wc -l [Note: This will have permission issues ] The following one is even better: UserParameter=postfix.queue,mailq | grep -v "Mail queue is empty" | grep -c '[1] ' Check

Creating a NFS Share

Create a directory to share mkdir /var/share vi /etc/exports /var/share 192.168.100.100(ro,no_root_squash,sync) Now to apply changes you can : exportfs -a To verify : exportfs For the first time , you want to restart the services : service nfs start service portmap start Mounting

Shell Script to check filesize

#!/bin/bash if [ $# -ne 1 ];then echo "0"; else /bin/ls -l $1 | awk '{print $5}'

Shell scripting tutorials

Doing an Arithmetic : i=$(( i * 5 )) Single Quotes: Ignoring special Characters : echo ‘*’ [ anything inside single quotes is ignored ] Double Quotes: Same as single quotes but not restrictive. The BackSlash: Equivalent to single quotes around a single character. Backslash quotes the single character $(…) Construct : $(command) is same as command and is

Regular Expressions

Period (.) = Match any single character **Caret (^) **= Match the begining of the line Dollar ($) = Match the end of the line **[…] **= Match a choice of characters eg. [abcABC] Asterisk(*) = Matching zero or more characters {min,max} = Matching Precise number of characters: {…} Saving Matched Characters : ^$.$\1 : Matches first character on the line , and

FFMPEG Commands tips and tricks.

Getting Information from a file : ffmpeg -i filename.ext Turn images to a video sequence: ffmpeg -f image2 -i image%d.jpg video.mpg ( converts images labeled 1,2,3 into a video) Turn video to images: ffmpeg -i video.mpg image%d.jpg Reduce the volume of an audio

Call a url from bash script

curl "http://www.amitnepal.com?inquiry.php?id=2&question=test"

Useful Find Commands

Find Files by name: find /path -name filename find /tmp /home . $HOME -name Find Files Larger than 1Gb find /path -type f -size +1048576 Find with wildcard: find / -name file\*name Find and process find / -type f -mtime -3 | xargs tar -rf archieve.tar [should not use -c option here,

Bash Script to check if a host is alive

Script to check if a host is alive: #!/bin/bash ping -c 2 www.amitnepal.com > /dev/null if [ $? -eq 0 ]; then echo "Alive"; </br&

Adding a Start/Stop Script to chkconfig

In order to add a script to be manageable by chkconfig, you should create the /etc/init.d/example script that has the ability to start and stop script. Now put the following two comments around the header of the script # chkconfig: 345 80 20 </br&

Export Putty Sessions

regedit /e "%userprofile%\desktop\putty-registry.reg" HKEY_CURRENT_USER\Software\Simontatham

Sample mysql queries

Delete Rows based on output from a query : DELETE FROM Table1 WHERE EXISTS(SELECT 1 FROM Table2 WHERE Table2.Group = Table1.Group) or delete from Table1 where id in (select id from table1 inner join table2 on Table1.

Handling arguments in bash

#!/bin/bash echo Total Number of Arguments Passed: $# i=1; for var in "$@" do echo "Argument $i

Handling parameters in Bash

Short Mode Only : #!/bin/bash while getopts :a:b:c opt #define options here : at the front supress error for unknown options do case $opt in&

Check Load average

uptime | awk ‘{print $10}’ | sed ‘s/,//g’

Nice and Renice

Nice command can be used to start a process with low/high priority: nice -n command value = -20 for highest priority and 20 for lowest priority To reset the priority of a running process, find the pid of the process and run: renice renice +1 102 -u daemon root -p

Shell Script to Backup and Rotate Mysql Database

#!/bin/bash #Author : Amit K Nepal #Last Modified : Nov 01 2011 BACKUP_DIR=/db_backups DB_NAME=dbname TSTAMP=`date

Writing Iptables rules by hand

*nat :PREROUTING ACCEPT [92:7226] :POSTROUTING ACCEPT [62:3916] :OUTPUT ACCEPT [62:3916] COMMIT *filter :INPUT DROP [0:0] :FORWARD DROP [0:0] :OUTPUT ACCEPT [0:0] COMMIT

Sample Kickstart file for Redhat / Centos

platform=x86, AMD64, or Intel EM64T # System authorization information auth --useshadow --enablemd5 # System bootloader configuration bootloader --location=mbr --password=grub # Clear the Master Boot Record zerombr # Partition clearing information clearpart --all --initlabel # Use text mode install text # Firewall configuration firewall --enabled --http --ftp --ssh --telnet --smtp # Run the Setup Agent

write to a file using php

$myFile = "testFile.txt"; $fh = fopen($myFile, 'a') or die("can't open file"); $stringData = "New Stuff 1\n"; fwrite($fh, $stringData); $stringData = "New Stuff 2\n"; fwrite($fh, $stringData); fclose($fh);