# Search inside text file
$ gradle run | less // search in 'gradle run' command
/searchWord // search from first
?searchWord // search from last
:q // quite search
# Finding a File Containing a Particular Text String
# Pass --color to grep command, displays matched text/words in color on terminal
$ grep -R --color "sampleWord" <directory>
$ sudo find / -type f -name '._*' # find files with regular expression
$ sudo find / -type f -name jenkins.xml # find a file
$ sudo find / -type d -name jenkins # find a directory
$ sudo find / -type d -name plugins -ls
$ sudo time <command> # return the time
# Search 'science(ignore lower/upper)' in science.txt file
$ grep -i science science.txt
$ wc -w science.txt // Count word
$ wc -l science.txt // Count lines
- Permissions:
1 -- can execute 2 -- can write 4 -- can read - The octal number is the sum of those free permissions:
- 3(1+2) - can execute and write - 6(2+4) - can write and read - Position of the digit in value:
1 - what owner can 2 - what users in the file group(class) can 3 - what users not in the file group(class) can
- Examples:
chmod 600 file - owner can read and write chmod 700 file - owner can read, write and execute chmod 666 file - all can read and write chmod 777 file - all can read, write and execute
$ sudo visudo
root ALL=(ALL:ALL) ALL
jenkins ALL=(ALL:ALL) ALL
$ lshw # show all hardware details
$ lshw -C display # show display details$ ssh-keygen -lf ~/.ssh/id_rsa.pub
$ ssh-keygen -R <ip_address / host_name>
$ eval "$(ssh-agent)"
$ ssh-add ~/.ssh/id_rsa # add ssh key to list of agent identites
$ ssh-add -l # you can see the agent just added
$ sudo nano /etc/ssh/ssh_config # open ssh_config file and add two lines down
Host <my-servers.com>
ForwardAgent yes
echo "$SSH_AUTH_SOCK"
- Bitbucket/GitHub does not allow us to use the same SSH key with more than one Bitbucket account.
-
Generate SSH Key:
$ ssh-keygen -t rsa -C <email@example.com> -
For multiple Bitbucket accounts (or GitHub) we need multiple SSH Keys. Generate another ssh key with a different name 'accountB':
$ ssh-keygen -t rsa -f ~/.ssh/accountB -C "email@example.com" -
Create config file '~/.ssh/config' with contains similar to:
$ nano ~/.ssh/config
// paste this
Host bitbucket.org
User git
Hostname bitbucket.org
PreferredAuthentications publickey
IdentityFile ~/.ssh/id_rsa
Host bitbucket-accountB
User git
Hostname bitbucket.org
PreferredAuthentications publickey
IdentitiesOnly yes
IdentityFile ~/.ssh/accountB-
Now clone from default account
$ git clone git@bitbucket.org:username/project.git -
Clone from accountB account
$ git clone git@bitbucket-accountB:username/project.git
$sudo apt-key adv --keyserver keyserver.ubuntu.com --recv-keys < add keys here >
$sudo chown -R <username>:<group> <directory>
$ ls -l 'which java'
/usr/libexec/java_home # where is java home directory
$ cat /etc/passwd
$ sudo adduser <username> # add a user
$ passwd <username> # change password for a user
Blue color -- Directory
Green color -- Executable or recognized data file
Sky Blue Color -- Linked file
yellow with black background -- device
Pink colour -- graphic image file
Red -- Archive file
For more informations type 'man dir_colors' in terminal.
$ date # show today's date
$ cal # show calendar
$ top # show all the process, CPU/Memory usage etc.
$ man <command-name> # get the details of a command (help)
$ ifconfig # show the ip address
$ ip addr show eth0 # show the details of 'eth0' (ethernet 0)
$ cat <file> | pbcopy # copy the contant of the file in clipboard
$ uname # print operating system name
$ uname -a # print hardware, nodename, processor architecture, os release, os name + version
$ uname -v # karnel version
$ uname -r # karnel release
$ lsb_release -a # see ubuntu version
$ df -ah # show the disk free (df), all human readable (-ah)
$ arch # print architecture type
# Short files by size (human readable output)
$ du <dir> --human-readable | sort --human-numeric-sort
$ ls <dir> --sort=size -la
$ du -ma | sort -nr | head -n 20 # show 20 largest files/folders under the current directory
# See the total size of directory
$ du -sh <path> # check the size (du -> disk use) of a directory's content on disk
$ du -h # show all sub directory size
# Give a access permission of a file
$ chmod 777 /var/run/docker.sock
$ ps wwaux | grep jenkins # Get PID
$ dd if=/dev/zero of=/swap bs=1M count=8024;mkswap /swap;swapon /swap;echo "/swap swap swap defaults 0 0" >> /etc/fstab # Add swap area in DO
$ netstat -tulpn | grep 8080 # Port status
$ df # See the drive and usage
# Check if mongodb is running
$ ps -ef | grep mongod | grep -v grep | wc -l | tr -d ' '
# Check if redis is running
$ redis-cli ping // PONG
# Restart mongodb service
$ brew services restart mongodb-community
# See the running process
$ pstree # pstree 1152
$ ps wwaux | grep jenkins
$ ps wwaux | grep postg
# See ip address
$ ip addr
# change password
$ sudo passwd
# Give sudo password with command in a line
$ echo 'Hello' | sudo -S apt-get update
# Show all user
$ compgen -u
# Change / Reset mysql db password
$ sudo mysqladmin -u root -p<old-password> password '<new-password>'
# sync two directories
$ rsync -a --progress <source> <destination>
# mv can't do merging/replacing, error: 'Directory not empty'
# Send file to remote machine through terminal
$ scp remote_user@remote_host:/path/to/remote/file /path/to/local/file
# Send jenkins_global_config file to remote globalConfig folder (scp source destination.. I prefer)
$ scp /home/sajib/TigerWorks/Source/dockerfiles/jenkins/jenkins_global_config/ root@45.55.247.59:/root/dockerfiles/jenkins/globalConfig/
$ sudo kill 'sudo lsof -t -i:9090'
$ sudo lsof -t -i:24007 # get the pid of 24007 port, say 123
$ kill 123 # kill the process
$ kill -9 <pid> # kill the process (go)$ sudo python3 -m http.server 80$ npm install ngrok -g
$ ngrok http <server-port>
# we will get ip address-
Converting video files to different formats. e.g. mp4 to avi
$ ffmpeg -i video.mp4 video.avi
-
Perform an exact copy of both the audio and video streams into the new file
$ ffmpeg -i input.mov -acodec copy -vcodec copy output.mp4
$ find . -name '*.js' | xargs wc -l
# if file name contains special character like spaces
$ find . -name '*.js' | sed 's/.*/"&"/' | xargs wc -l
# sorted output
$ find . -name '*.js' | xargs wc -l | sort -nr
C + a: Move to the start of the line.
C + e: Move to the end of the line.
C + l: Clear the screen, reprinting the current line at the top.
M + f: Move forward a word, where a word is composed of letters and digits.
M + b: Move backward a word.
- C-k Kill the text from the current cursor position to the end of the line.
- M-d Kill from the cursor to the end of the current word, or, if between words, to the end of the next word. Word boundaries are the same as those used by M-f.
- M-[DEL] Kill from the cursor the start of the current word, or, if between words, to the start of the previous word. Word boundaries are the same as those used by M-b.
- C-w Kill from the cursor to the previous whitespace. This is different than M- because the word boundaries differ.
- C-y Yank the most recently killed text back into the buffer at the cursor.
- M-y Rotate the kill-ring, and yank the new top. You can only do this if the prior command is C-y or M-y.
ls, cd, mv, mkdir, rm
- Additional basic commands:
- pwd - Print Working Directory
- cd - Change Directory
- ls - LiSt directory contents
- echo, cat, man, pwd, cp, ln, less, grep, tail, ssh, reboot, poweroff
- Bonus
- vim
But really, a programmer needs more than that.
WARNING: The following packages cannot be authenticated!
Solutions: $ apt-get install debian-archive-keyring