Archive

Articles taggués ‘bash’

Alertes par SMS en Bash (via Google Calendar)

26/09/2018 Comments off

La remontée d’alerte par SMS (“Short Message Service”) est un plus non négligeable dans le monitoring de systèmes d’informations critiques.

Les services gratuits permettant d’utiliser les SMS depuis le système restent rare.

Depuis plusieurs années déjà, “Google Agenda” propose à ses clients des rappels de rendez-vous par SMS.
Rapidement, ce service Google fût détourné pour être utilisé comme source de remontée d’alertes (exemple : “SmsAlert : Envoyer des SMS gratuitement depuis ses serveurs” sur le site Macsim’s Mind qui utilisait le script PHP d’ Alexander Skakunov pour remonter des alertes par SMS).

Bien que très efficaces, la plupart de ces détournement sont implémentés en PHP qui n’est pas installé sur tous les serveurs.

L’idée de cet article et d’utiliser la même technique mais implémentée en BASH.

Principe de fonctionnement

Le principe est de créer un événement dans un agenda Google Calendar débutant dans 5 minutes et X secondes et d’avertir l’administrateur par SMS 5 minutes avant le début de l’événement. Le SMS sera donc envoyé après X secondes.

L’objectif du script “googalert” (disponible sur sourceforge) est de n’utiliser que des commandes classiques du shell, de pouvoir choisir l’agenda dans lesquels seront stockés les alertes et d’être parfaitement conforme à l’API Google(http://www.udel.edu/CIS/software/dist/google/calendar/java.client/gdata/doc/calendar.htmlvoir Add an event).

Lire la suite…

Categories: Système Tags: , , ,

30 Handy Bash Shell Aliases For Linux / Unix / Mac OS X

28/09/2017 Comments off

An alias is nothing but the shortcut to commands. The alias command allows the user to launch any command or group of commands (including options and filenames) by entering a single word. Use alias command to display a list of all defined aliases. You can add user-defined aliases to ~/.bashrcfile. You can cut down typing time with these aliases, work smartly, and increase productivity at the command prompt.

More about aliases

The general syntax for the alias command for the bash shell is as follows:

Task: List aliases

Type the following command:

alias

Sample outputs:

alias ..='cd ..'
alias amazonbackup='s3backup'
alias apt-get='sudo apt-get'
...

By default alias command shows a list of aliases that are defined for the current user.

Task: Define / create an alias (bash syntax)

To create the alias use the following syntax:

alias name=value
alias name='command'
alias name='command arg1 arg2'
alias name='/path/to/script'
alias name='/path/to/script.pl arg1'

In this example, create the alias c for the commonly used clear command, which clears the screen, by typing the following command and then pressing the ENTER key:

alias c='clear'

Then, to clear the screen, instead of typing clear, you would only have to type the letter ‘c’ and press the [ENTER] key:

c

Task: Disable an alias temporarily (bash syntax)

An alias can be disabled temporarily using the following syntax:

## path/to/full/command
/usr/bin/clear
## call alias with a backslash ##
\c

Task: Remove an alias (bash syntax)

You need to use the command called unalias to remove aliases. Its syntax is as follows:

unalias aliasname

In this example, remove the alias c which was created in an earlier example:

unalias c

You also need to delete the alias from the ~/.bashrc file using a text editor (see next section).

Task: Make aliases permanent (bash syntax)

The alias c remains in effect only during the current login session. Once you logs out or reboot the system the alias c will be gone. To avoid this problem, add alias to your ~/.bashrc file, enter:

vi ~/.bashrc

The alias c for the current user can be made permanent by entering the following line:

alias c='clear'

Save and close the file. System-wide aliases (i.e. aliases for all users) can be put in the /etc/bashrc file. Please note that the alias command is built into a various shells including ksh, tcsh/csh, ash, bash and others.

A note about privileged access

You can add code as follows in ~/.bashrc:

# if user is not root, pass all commands via sudo #
if [ $UID -ne 0 ]; then
    alias reboot='sudo reboot'
    alias update='sudo apt-get upgrade'
fi

A note about os specific aliases

You can add code as follows in ~/.bashrc using the case statement:

### Get os name via uname ###
_myos="$(uname)"
 
### add alias as per os using $_myos ###
case $_myos in
   Linux) alias foo='/path/to/linux/bin/foo';;
   FreeBSD|OpenBSD) alias foo='/path/to/bsd/bin/foo' ;;
   SunOS) alias foo='/path/to/sunos/bin/foo' ;;
   *) ;;
esac

30 uses for aliases

You can define various types aliases as follows to save time and increase productivity.

#1: Control ls command output

The ls command lists directory contents and you can colorize the output:

## Colorize the ls output ##
alias ls='ls --color=auto'
 
## Use a long listing format ##
alias ll='ls -la'
 
## Show hidden files ##
alias l.='ls -d .* --color=auto'

#2: Control cd command behavior

## get rid of command not found ##
alias cd..='cd ..'
 
## a quick way to get out of current directory ##
alias ..='cd ..'
alias ...='cd ../../../'
alias ....='cd ../../../../'
alias .....='cd ../../../../'
alias .4='cd ../../../../'
alias .5='cd ../../../../..'

#3: Control grep command output

grep command is a command-line utility for searching plain-text files for lines matching a regular expression:

## Colorize the grep command output for ease of use (good for log files)##
alias grep='grep --color=auto'
alias egrep='egrep --color=auto'
alias fgrep='fgrep --color=auto'

#4: Start calculator with math support

alias bc='bc -l'

#4: Generate sha1 digest

alias sha1='openssl sha1'

#5: Create parent directories on demand

mkdir command is used to create a directory:

alias mkdir='mkdir -pv'

#6: Colorize diff output

You can compare files line by line using diff and use a tool called colordiff to colorize diff output:

# install colordiff package 🙂
alias diff='colordiff'

#7: Make mount command output pretty and human readable format

alias mount='mount |column -t'

#8: Command short cuts to save time

# handy short cuts #
alias h='history'
alias j='jobs -l'

#9: Create a new set of commands

alias path='echo -e ${PATH//:/\\n}'
alias now='date +"%T"'
alias nowtime=now
alias nowdate='date +"%d-%m-%Y"'

#10: Set vim as default

alias vi=vim
alias svi='sudo vi'
alias vis='vim "+set si"'
alias edit='vim'

#11: Control output of networking tool called ping

# Stop after sending count ECHO_REQUEST packets #
alias ping='ping -c 5'
# Do not wait interval 1 second, go fast #
alias fastping='ping -c 100 -s.2'

#12: Show open ports

Use netstat command to quickly list all TCP/UDP port on the server:

alias ports='netstat -tulanp'

#13: Wakeup sleeping servers

Wake-on-LAN (WOL) is an Ethernet networking standard that allows a server to be turned on by a network message. You can quickly wakeup nas devices and server using the following aliases:

## replace mac with your actual server mac address #
alias wakeupnas01='/usr/bin/wakeonlan 00:11:32:11:15:FC'
alias wakeupnas02='/usr/bin/wakeonlan 00:11:32:11:15:FD'
alias wakeupnas03='/usr/bin/wakeonlan 00:11:32:11:15:FE'

#14: Control firewall (iptables) output

Netfilter is a host-based firewall for Linux operating systems. It is included as part of the Linux distribution and it is activated by default. This post list most common iptables solutions required by a new Linux user to secure his or her Linux operating system from intruders.

## shortcut for iptables and pass it via sudo#
alias ipt='sudo /sbin/iptables'
 
# display all rules #
alias iptlist='sudo /sbin/iptables -L -n -v --line-numbers'
alias iptlistin='sudo /sbin/iptables -L INPUT -n -v --line-numbers'
alias iptlistout='sudo /sbin/iptables -L OUTPUT -n -v --line-numbers'
alias iptlistfw='sudo /sbin/iptables -L FORWARD -n -v --line-numbers'
alias firewall=iptlist

#15: Debug web server / cdn problems with curl

# get web server headers #
alias header='curl -I'
 
# find out if remote server supports gzip / mod_deflate or not #
alias headerc='curl -I --compress'

#16: Add safety nets

# do not delete / or prompt if deleting more than 3 files at a time #
alias rm='rm -I --preserve-root'
 
# confirmation #
alias mv='mv -i'
alias cp='cp -i'
alias ln='ln -i'
 
# Parenting changing perms on / #
alias chown='chown --preserve-root'
alias chmod='chmod --preserve-root'
alias chgrp='chgrp --preserve-root'

#17: Update Debian Linux server

apt-get command is used for installing packages over the internet (ftp or http). You can also upgrade all packages in a single operations:

# distro specific - Debian / Ubuntu and friends #
# install with apt-get
alias apt-get="sudo apt-get"
alias updatey="sudo apt-get --yes"
 
# update on one command
alias update='sudo apt-get update && sudo apt-get upgrade'

#18: Update RHEL / CentOS / Fedora Linux server

yum command is a package management tool for RHEL / CentOS / Fedora Linux and friends:

## distrp specifc RHEL/CentOS ##
alias update='yum update'
alias updatey='yum -y update'

#19: Tune sudo and su

# become root #
alias root='sudo -i'
alias su='sudo -i'

#20: Pass halt/reboot via sudo

shutdown command bring the Linux / Unix system down:

# reboot / halt / poweroff
alias reboot='sudo /sbin/reboot'
alias poweroff='sudo /sbin/poweroff'
alias halt='sudo /sbin/halt'
alias shutdown='sudo /sbin/shutdown'

#21: Control web servers

# also pass it via sudo so whoever is admin can reload it without calling you #
alias nginxreload='sudo /usr/local/nginx/sbin/nginx -s reload'
alias nginxtest='sudo /usr/local/nginx/sbin/nginx -t'
alias lightyload='sudo /etc/init.d/lighttpd reload'
alias lightytest='sudo /usr/sbin/lighttpd -f /etc/lighttpd/lighttpd.conf -t'
alias httpdreload='sudo /usr/sbin/apachectl -k graceful'
alias httpdtest='sudo /usr/sbin/apachectl -t && /usr/sbin/apachectl -t -D DUMP_VHOSTS'

#22: Alias into our backup stuff

# if cron fails or if you want backup on demand just run these commands #
# again pass it via sudo so whoever is in admin group can start the job #
# Backup scripts #
alias backup='sudo /home/scripts/admin/scripts/backup/wrapper.backup.sh --type local --taget /raid1/backups'
alias nasbackup='sudo /home/scripts/admin/scripts/backup/wrapper.backup.sh --type nas --target nas01'
alias s3backup='sudo /home/scripts/admin/scripts/backup/wrapper.backup.sh --type nas --target nas01 --auth /home/scripts/admin/.authdata/amazon.keys'
alias rsnapshothourly='sudo /home/scripts/admin/scripts/backup/wrapper.rsnapshot.sh --type remote --target nas03 --auth /home/scripts/admin/.authdata/ssh.keys --config /home/scripts/admin/scripts/backup/config/adsl.conf'
alias rsnapshotdaily='sudo /home/scripts/admin/scripts/backup/wrapper.rsnapshot.sh --type remote --target nas03 --auth /home/scripts/admin/.authdata/ssh.keys --config /home/scripts/admin/scripts/backup/config/adsl.conf'
alias rsnapshotweekly='sudo /home/scripts/admin/scripts/backup/wrapper.rsnapshot.sh --type remote --target nas03 --auth /home/scripts/admin/.authdata/ssh.keys --config /home/scripts/admin/scripts/backup/config/adsl.conf'
alias rsnapshotmonthly='sudo /home/scripts/admin/scripts/backup/wrapper.rsnapshot.sh --type remote --target nas03 --auth /home/scripts/admin/.authdata/ssh.keys --config /home/scripts/admin/scripts/backup/config/adsl.conf'
alias amazonbackup=s3backup

#23: Desktop specific – play avi/mp3 files on demand

## play video files in a current directory ##
# cd ~/Download/movie-name
# playavi or vlc
alias playavi='mplayer *.avi'
alias vlc='vlc *.avi'
 
# play all music files from the current directory #
alias playwave='for i in *.wav; do mplayer "$i"; done'
alias playogg='for i in *.ogg; do mplayer "$i"; done'
alias playmp3='for i in *.mp3; do mplayer "$i"; done'
 
# play files from nas devices #
alias nplaywave='for i in /nas/multimedia/wave/*.wav; do mplayer "$i"; done'
alias nplayogg='for i in /nas/multimedia/ogg/*.ogg; do mplayer "$i"; done'
alias nplaymp3='for i in /nas/multimedia/mp3/*.mp3; do mplayer "$i"; done'
 
# shuffle mp3/ogg etc by default #
alias music='mplayer --shuffle *'

#24: Set default interfaces for sys admin related commands

vnstat is console-based network traffic monitor. dnstop is console tool to analyze DNS traffic. tcptrack and iftop commands displays information about TCP/UDP connections it sees on a network interface and display bandwidth usage on an interface by host respectively.

## All of our servers eth1 is connected to the Internets via vlan / router etc ##
alias dnstop='dnstop -l 5 eth1'
alias vnstat='vnstat -i eth1'
alias iftop='iftop -i eth1'
alias tcpdump='tcpdump -i eth1'
alias ethtool='ethtool eth1'
 
# work on wlan0 by default #
# Only useful for laptop as all servers are without wireless interface
alias iwconfig='iwconfig wlan0'

#25: Get system memory, cpu usage, and gpu memory info quickly

## pass options to free ##
alias meminfo='free -m -l -t'
 
## get top process eating memory
alias psmem='ps auxf | sort -nr -k 4'
alias psmem10='ps auxf | sort -nr -k 4 | head -10'
 
## get top process eating cpu ##
alias pscpu='ps auxf | sort -nr -k 3'
alias pscpu10='ps auxf | sort -nr -k 3 | head -10'
 
## Get server cpu info ##
alias cpuinfo='lscpu'
 
## older system use /proc/cpuinfo ##
##alias cpuinfo='less /proc/cpuinfo' ##
 
## get GPU ram on desktop / laptop##
alias gpumeminfo='grep -i --color memory /var/log/Xorg.0.log'

#26: Control Home Router

The curl command can be used to reboot Linksys routers.

# Reboot my home Linksys WAG160N / WAG54 / WAG320 / WAG120N Router / Gateway from *nix.
alias rebootlinksys="curl -u 'admin:my-super-password' 'http://192.168.1.2/setup.cgi?todo=reboot'"
 
# Reboot tomato based Asus NT16 wireless bridge
alias reboottomato="ssh admin@192.168.1.1 /sbin/reboot"

#27 Resume wget by default

The GNU Wget is a free utility for non-interactive download of files from the Web. It supports HTTP, HTTPS, and FTP protocols, and it can resume downloads too:

## this one saved by butt so many times ##
alias wget='wget -c'

#28 Use different browser for testing website

## this one saved by butt so many times ##
alias ff4='/opt/firefox4/firefox'
alias ff13='/opt/firefox13/firefox'
alias chrome='/opt/google/chrome/chrome'
alias opera='/opt/opera/opera'
 
#default ff
alias ff=ff13
 
#my default browser
alias browser=chrome

#29: A note about ssh alias

Do not create ssh alias, instead use ~/.ssh/config OpenSSH SSH client configuration files. It offers more option. An example:

Host server10
  Hostname 1.2.3.4
  IdentityFile ~/backups/.ssh/id_dsa
  user foobar
  Port 30000
  ForwardX11Trusted yes
  TCPKeepAlive yes

You can now connect to peer1 using the following syntax:
$ ssh server10

#30: It’s your turn to share…

## set some other defaults ##
alias df='df -H'
alias du='du -ch'
 
# top is atop, just like vi is vim
alias top='atop'
 
## nfsrestart - must be root ##
## refresh nfs mount / cache etc for Apache ##
alias nfsrestart='sync && sleep 2 && /etc/init.d/httpd stop && umount netapp2:/exports/http && sleep 2 && mount -o rw,sync,rsize=32768,wsize=32768,intr,hard,proto=tcp,fsc natapp2:/exports /http/var/www/html && /etc/init.d/httpd start'
 
## Memcached server status ##
alias mcdstats='/usr/bin/memcached-tool 10.10.27.11:11211 stats'
alias mcdshow='/usr/bin/memcached-tool 10.10.27.11:11211 display'
 
## quickly flush out memcached server ##
alias flushmcd='echo "flush_all" | nc 10.10.27.11 11211'
 
## Remove assets quickly from Akamai / Amazon cdn ##
alias cdndel='/home/scripts/admin/cdn/purge_cdn_cache --profile akamai'
alias amzcdndel='/home/scripts/admin/cdn/purge_cdn_cache --profile amazon'
 
## supply list of urls via file or stdin
alias cdnmdel='/home/scripts/admin/cdn/purge_cdn_cache --profile akamai --stdin'
alias amzcdnmdel='/home/scripts/admin/cdn/purge_cdn_cache --profile amazon --stdin'

Conclusion

This post summarizes several types of uses for *nix bash aliases:

  1. Setting default options for a command (e.g. set eth0 as default option for ethtool command via alias ethtool='ethtool eth0' ).
  2. Correcting typos (cd.. will act as cd .. via alias cd..='cd ..').
  3. Reducing the amount of typing.
  4. Setting the default path of a command that exists in several versions on a system (e.g. GNU/grep is located at /usr/local/bin/grep and Unix grep is located at /bin/grep. To use GNU grep use alias grep='/usr/local/bin/grep' ).
  5. Adding the safety nets to Unix by making commands interactive by setting default options. (e.g. rm, mv, and other commands).
  6. Compatibility by creating commands for older operating systems such as MS-DOS or other Unix like operating systems (e.g. alias del=rm ).

I’ve shared my aliases that I used over the years to reduce the need for repetitive command line typing. If you know and use any other bash/ksh/csh aliases that can reduce typing, share below in the comments.

Categories: Système Tags: , , ,

How to check the file size in Linux/Unix bash shell scripting

28/09/2017 Comments off

 

How to check file size in unix using wc command

The wc command shows the number of lines, words, and bytes contained in file. The syntax is as follows to get the file size:
wc -c /path/to/file
wc -c /etc/passwd

Sample outputs:

5253 /etc/passwd

You can easily extract the first field either using the cut or awk command:
wc -c /etc/passwd | awk '{print $1}'
Sample outputs:

5253

OR assign this size to a bash variable:

myfilesize=$(wc -c "/etc/passwd" | awk '{print $1}')
printf "%d\n" $myfilesize
echo "$myfilesize"

How to get the size of a file in a bash script using stat command

The stat command shows information about the file. The syntax is as follows to get the file size on GNU/Linux stat:
stat -c %s "/etc/passwd"
OR
stat --format=%s "/etc/passwd"
To assign this size to a bash variable:

myfilesize=$(stat --format=%s "/etc/passwd")
echo "$myfilesize"
## or ##
myFileSizeCheck=$(stat -c %s "/etc/resolv.conf")
printf "My file size = %d\n" $myFileSizeCheck

The syntax is as follows to get the file size on BSD/MacOS stat:
stat -f %z "/etc/passwd"
Please note that if the file is symlink you will get size of that link only with the stat command.

du command example

The syntax is

du --apparent-size --block-size=1  "/etc/passwd"
fileName="/etc/hosts"
mfs=$(du --apparent-size --block-size=1  "$fileName" | awk '{ print $1}')
echo "$fileName size = ${mfs}"

Sample outputs from above commands:

Fig.01: How to check size of a file using a bash/ksh/zsh/sh/tcsh shell?Fig.01: How to check size of a file using a bash/ksh/zsh/sh/tcsh shell?

 

Find command example

The syntax is:

find "/etc/passwd" -printf "%s"
find "/etc/passwd" -printf "%s\n"
fileName="/etc/hosts"
mysize=$(find "$fileName" -printf "%s")
printf "File %s size = %d\n" $fileName $mysize
echo "${fileName} size is ${mysize} bytes."
Categories: Système Tags: , , , , ,

How to get domain name from URL in bash shell script

28/09/2017 Comments off
How can I extract or fetch a domain name from a URL string (e.g. https://www.cyberciti.biz/index.php) using bash shell scripting under Linux or Unix-like operating system?

You can use standard Unix commands such as sed, awk, grep, Perl, Python and more to get domain name from URL. No need to write regex. It is pretty simple.

Let use see various commands and option to grab the domain part from given variable under Linux or Unix-like system.

Get domain name from full URL

Say your url name is stored in a bash shell variable such as $x:
x='https://www.dbsysnet.com/'
You can use the awk as follows:
echo "$x" | awk -F/ '{print $3}'
### OR ###
awk -F/ '{print $3}' <<<$x

Sample outputs:

www.dbsysnet.com

Extract domain name from URL using sed

Here is a sample sed command:
url="https://www.dbsysnet.com"
echo "$url" | sed -e 's|^[^/]*//||' -e 's|/.*$||'

Extract domain name from URL using bash shell parameter substitution

Another option is to use bash shell parameter substitution:

# My shell variable 
f="https://www.cyberciti.biz/faq/copy-command/"
 
## Remove protocol part of url ##
f="${f#http://}"
f="${f#https://}"
f="${f#ftp://}"
f="${f#scp://}"
f="${f#scp://}"
f="${f#sftp://}"
 
## Remove username and/or username:password part of URL ##
f="${f#*:*@}"
f="${f#*@}"
 
## Remove rest of urls ##
f=${f%%/*}
 
## Show domain name only ##
echo "$f"

Shell script example

A shell script to purge urls from Cloudflare by matching domain name part:

#!/bin/bash
zone_id=""
api_key=""
 
urls="$@"
bon=$(tput bold)
boff=$(tput sgr0)
c=1
[ "$urls" == "" ] && { echo "Usage: $0 url"; exit 1; }
 
clear
echo "Purging..."
echo
for u in $urls
do
     echo -n "${bon}${c}${boff}.${u}: "
     ## Get domain name ##
     d="$(echo $u | awk -F/ '{ print $3}')"
     ## Set API_KEY, Email_ID, and ZONE_ID as per domain ##
     case $d in
	     www.cyberciti.biz) zone_id="ID_1"; api_key="MY_KEY_1"; email_id="webmaster@cyberciti.biz";;
	     theos.in) zone_id="ID_2"; api_key="MY_KEY_2"; email_id="webmaster@theos.in";;
	     *) echo "Domain not configured."; continue;;
     esac
     ## Do it ##
     curl -X DELETE "https://api.cloudflare.com/client/v4/zones/${zone_id}/purge_cache" \
     -H "X-Auth-Email: ${email_id}" \
     -H "X-Auth-Key: ${api_key}" \
     -H "Content-Type: application/json" \
     --data "{\"files\":[\"${u}\"]}"
     echo
     (( c++ ))
done
echo
Categories: Système Tags: , , ,

How to count total number of word occurrences using grep on Linux or Unix

28/09/2017 Comments off

I want to find out how many times a word (say foo or an IP address) occurs in a text file using the grep command on Linux or Unix-like system?

You can use the grep command to search strings, words, text, and numbers for a given patterns. You can pass the -coption to grep command. It only shows the number of times that the pattern has been matched for each file.

 

 

 

Show the total number of times that the word foo appears in a file named bar.txt

The syntax is:
grep -c string filename
grep -c foo bar.txt

Sample outputs:

3

To count total number of occurrences of word in a file named /etc/passwd root using grep, run:
grep -c root /etc/passwd
To verify that run:
grep --color root /etc/passwd
Pass the -w option to grep to select only an entire word or phrase that matches the specified pattern:
grep -w root /etc/passwd
OR
grep -c -w root /etc/passwd
In this example only match a word being with root:
grep --color -w '^root' /etc/passwd
grep -c -w '^root' /etc/passwd

To show only the matching part of the lines.
grep -o 'root' /etc/passwd
grep -c -o 'root' /etc/passwd

Sample session:

Fig.01: Counting occurrence of words/strings using grep commandFig.01: Counting occurrence of words/strings using grep command