My Linux commands cheatsheet

The following Linux commands compilation are my personal Linux commands that I find useful in my daily work:

Display running tasks:

top

or

htop

Display current process running:

ps ax

or

ps -ef

Backup a mysq database:

mysqldump -u [uname] -p [dbname] > [backupfile.sql]

Restore a mysq database from backup file:

mysql -u [uname] -p [dbname] 

List all storage partition:

fdisk -l

Display disk space usage:

df -h

Search or find big files Linux (50MB) in current directory:

find . -type f -size +50000k -exec ls -lh {} \; | awk '{ print $9 ": " $5 }'

Change file ownership recusively:

chown -R apache:apache /var/htdocs

Create a directory with no error if existing and auto create parent directories as needed:

mkdir -p newfolder/innerfolder/

Copy files recursively:

cp -rf /var/htdocs /home/roland/public_html

Delete files recusively:

rm -rf /var/htdocs

Copy file from local computer to remote computer (scp ):

scp backup.tar.gz [email protected]:/home/roland

Copy file from remote computer to local computer (scp ):

scp [email protected]:/home/roland/backup.tar.gz /download/

Compressing using tar:

tar zcvf backup.tar.gz /backup/*

Extracting tar:

tar zxvf backup.tar.gz

Extracting gzip:

gunzip backup.gz

Download a file from remote site:

wget http://ftp.drupal.org/files/projects/drupal-8.x-dev.tar.gz

or

curl -O http://ftp.drupal.org/files/projects/drupal-8.x-dev.tar.gz

Check and install a software:

which java
yum list available java*
yum install java-1.8.0-openjdk.x86_64
which java
java -version

Display content of a text file:

cat README.txt

Edit a file with VIM:

vi index.php

Delete all hidden svn folders:

find . -name *svn -print0 | xargs -0 rm -rf

or

rm -rf `find . -type d -name .svn`

Compare files including sub folders:

diff -bwBqr "!tinymce" htdocs\sites\all\libraries\tinymce > diff.txt

Compare and auto patch:

diff -bwBu old.txt new.txt | patch old.txt

Network commands:

ifconfig
ifup eth0
ifdown eth0
netconfig

Soft linking a file:

ln -s ttyCL0 ttyS0

Test if port is open/listening

netstat -tuplen
nc 127.0.0.1 8080 

or

nmap -p 8080 127.0.0.1

Health check of a webpage:

curl -Sf www.webfoobar.com/node/1 > /dev/null

Health check of a webpage bypassing CDN:

curl -H 'Host: www.webfoobar.com' -s -D - -o /dev/null 'http://xxx.xxx.xxx.xxx/node/1'

Add port (to specific line number, eg. 5) to unblock it from firewall and backup the rules:

iptables -I INPUT 5 -p tcp -m tcp --dport 8080 -j ACCEPT
iptables --line -vnL
service iptables save
service iptables restart
iptables-save > /home/roland/conf.bak/iptables.bak

Restore iptables rules from backup file:

iptables-restore < /home/roland/conf.bak/iptables.bak

Add a rule to iptables:

iptables -A INPUT -p tcp --dport 8080 -j ACCEPT
iptables --line -vnL
service iptables save
service iptables restart

Remove a rule from iptables:

iptables -D INPUT -p tcp --dport 8080 -j ACCEPT
iptables --line -vnL
service iptables save
service iptables restart

Shows successful login attempts:

last

Shows bad login attempts:

lastb

or:

cat /var/log/secure | grep 'sshd.*Invalid'

Watch last 20 log of failed attempts refreshing every one second:

watch -n 1 tail -n 20 /var/log/secure

Block an IP:

iptables -A INPUT -s XXX.XXX.XXX.XXX -j DROP
service iptables save
service iptables restart

or edit /etc/hosts.deny to append:

ALL: XXX.XXX.XXX.XXX

Unblock an IP:

iptables -D INPUT -s XXX.XXX.XXX.XXX -j DROP
service iptables save
service iptables restart

Benchmark your site (Anonymous users):

ab -n 500 -c 10 -r [domain]
ab -n 500 -c 10 -r http://www.webfoobar.com/

Benchmark your site (Authenticated users):

ab -c 1 -n 100 -C [session name]=[session value] [domain]
ab -c 1 -n 100 -C SESS35ff2c61bdd320e6efaf60591161691a=OteOH_VuieYK9_Y-culzTEsQJevDfIjkUC50c-aO1BA http://www.webfoobar.com/

Log network traffic:

tcpdump -s 0 -i eth0 -w wireshark.pcap

List top IP network traffic:

netstat -plan|grep :80|awk {'print $5'}|cut -d: -f 1|sort|uniq -c|sort -nk 1

Monitor server resources (every 3 seconds refresh rate):

vmstat 3

Know the IP table in the network:

arp -a

Change user password:

passwd

Compile source code of a software:

autoreconf -i
./configure
make
make install

Hard Disk Clone:

dd if=/dev/sda of=/dev/sdb

Making a Hard Disk Image File:

dd if=/dev/sda of=sda.img

Restoring from an Image File:

dd if=sda.img of=/dev/sda

Logs out from SSH that prevents saving the current session's executed commands to bash history:

kill -9 $$