Send process to background:
Ctrl + z
Move process to foreground:
fg
Generate random hex number where n is number of characters:
openssl rand -hex n
Execute commands from a file in the current shell:
source /home/user/file.name
Substring for first 5 characters:
${variable:0:5}
SSH debug mode:
ssh -vvv user@ip_address
SSH with pem key:
ssh user@ip_address -i key.pem
Get complete directory listing to local directory with wget:
wget -r --no-parent --reject "index.html*" http://hostname/ -P /home/user/dirs
Create multiple directories:
mkdir -p /home/user/{test,test1,test2}
List processes tree with child processes:
ps axwef
Create war file:
jar -cvf name.war file
Test disk write speed:
dd if=/dev/zero of=/tmp/output.img bs=8k count=256k; rm -rf /tmp/output.img
Test disk read speed:
hdparm -Tt /dev/sda
Get md5 hash from text:
echo -n "text" | md5sum
Check xml syntax:
xmllint --noout file.xml
Extract tar.gz in new directory:
tar zxvf package.tar.gz -C new_dir
Get HTTP headers with curl:
curl -I http://www.example.com
Modify timestamp of some file or directory (YYMMDDhhmm):
touch -t 0712250000 file
Download from ftp using wget:
wget -m ftp://username:password@hostname
Generate random password (16 char long in this case):
LANG=c
Quickly create a backup of a file:
cp some_file_name{,.bkp}
Access Windows share:
smbclient -U "DOMAIN\user" //dc.domain.com/share/test/dir
Run command from history (here at line 100):
!100
Unzip to directory:
unzip package_name.zip -d dir_name
Multiline text (CTRL + d to exit):
cat > test.txt
Create empty file or empty existing one:
> test.txt
Update date from Ubuntu NTP server:
ntpdate ntp.ubuntu.com
netstat show all tcp4 listening ports:
netstat -lnt4 | awk '{print $4}' | cut -f2 -d: | grep -o '[0-9]*'
Convert image from qcow2 to raw:
qemu-img convert -f qcow2 -O raw precise-server-cloudimg-amd64-disk1.img \
precise-server-cloudimg-amd64-disk1.raw
Run command repeatedly, displaying it's output (default every two seconds):
watch ps -ef
List all users:
getent passwd
Mount root in read/write mode:
mount -o remount,rw /
Mount a directory (for cases when symlinking will not work):
mount --bind /source /destination
Send dynamic update to DNS server:
nsupdate
Recursively grep all directories:
grep -r "some_text" /path/to/dir
List ten largest open files:
lsof / | awk '{ if($7 > 1048576) print $7/1048576 "MB "$9 }' | sort -n -u | tail
Show free RAM in MB:
free -m | grep cache | awk '/[0-9]/{ print $4" MB" }'
Open Vim and jump to end of file:
vim + some_file_name
Git clone specific branch (master):
git clone
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:name/app.git -b master
Git switch to another branch (develop):
git checkout develop
Git delete branch (myfeature):
git branch -d myfeature
Git delete remote branch:
git push origin :branchName
Git push new branch to remote:
git push -u origin mynewfeature
Print out the last cat command from history:
!cat:p
Run your last cat command from history:
!cat
Find all empty subdirectories in /home/user:
find /home/user -maxdepth 1 -type d -empty
Get all from line 50 to 60 in test.txt:
Run last command (if it was: mkdir /root/test, below will run: sudo mkdir /root/test):
sudo !!
Create temporary RAM filesystem - ramdisk (first create /tmpram directory):
mount -t tmpfs tmpfs /tmpram -o size=512m
Grep whole words:
grep -w "name" test.txt
Append text to a file that requires raised privileges:
echo "some text" | sudo tee -a /path/file
List all supported kill signals:
kill -l
Generate random password (16 characters long in this case):
openssl rand -base64 16
Do not log last session in bash history:
kill -9 $$
Scan network to find open port:
nmap -p 8081 172.20.0.0/16
Set git email:
git config --global user.email "
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"
To sync with master if you have unpublished commits:
git pull --rebase origin master
Move all files with "txt" in name to /home/user:
find -iname "*txt*" -exec mv -v {} /home/user \;
Put the file lines side by side:
paste test.txt test1.txt
Progress bar in shell:
pv data.log
Send the data to Graphite server with netcat:
echo "hosts.sampleHost 10 `date +%s`" | nc 192.168.200.2 3000
Convert tabs to spaces:
expand test.txt > test1.txt
Skip bash history:
cmd
Go to the previous working directory:
cd -
Split large tar.gz archive (100MB each) and put it back:
split –b 100m /path/to/large/archive /path/to/output/files
cat files* > archive
Get HTTP status code with curl:
curl -sL -w "%{http_code}\\n" www.example.com -o /dev/null
Set root password and secure MySQL installation:
/usr/bin/mysql_secure_installation
When Ctrl + c not works:
Ctrl + \
Get file owner:
stat -c %U file.txt
