This guide is about useful linux commands that can be used on a terminal and can help a developer in his day to day activities. I have written this cheat sheet based on how hard it is to remember some of this commands and how it can be helpful to other developers.
Copying Files with Rsync From Server to Local Machine
There are several ways in which you can copy a file over ssh in linux, you can copy using rsync command or scp command. Rsync is faster than scp as it employs optimization algorithms. Rsync (Remote Sync) is a most commonly used command for copying and synchronizing files and directories remotely as well as locally in Linux/Unix systems
rsync options source destination
to copy a file from a server to current directory denoted by fullstop (.) in linux
rsync --stats root@192.168.0.100:/var/www/cassava.zip .
You can also use Rsync to copy files from local machine to the server
rsync --stats backup.tar root@192.168.0.100:/backups/
the file name is backup.tar and we are copying it to the directory /backups
Connect To MySQL Database From Command Line
This section expains how to connect to mySql from terminal over
replace username with your username, -p prompts for password
mysql -u USERNAME -p
Suppose you want to connect to a database with a different hostname and port number
mysql --host=hostname --port=port_number-u USERNAME -p
Replace host_name, port_number and USERNAME with your environment values.
History Command
The GNU history command keeps a list of all the other commands that have been run from that terminal session.
Suppose you are working on a new system and you do not know where the application lies, running history command can help.
history
suppose you connected to a server via ssh and you don't want to go and find the server username and ip_address. you can search in your history file using grep.
history | grep ssh
Find Command
Find is one of the most simple and useful commands in linux. Developers use find to search for a file or directory on your file system. Using the -exec flag, files can be found and immediately executed. The syntax of the find command is
find options starting/path expression
| find . -name backup.tar | Find the file whose name is backup.tar in the current working directory |
| find / -type d -name Cassavahub | d specifies directory, finds all directories with name Cassavahub in / directory |
| find . -type f -name cassavahub.php | finds file with name cassavahub.php in current directory |
| find / -type f -size +100M -exec rm -f {} \; | To find all 100MB files and delete them using one single command. |
You can view more information about find command here https://www.tecmint.com/35-practical-examples-of-linux-find-command/
Compressing files using Tar
Tar or Tap Archive is used to archive directories or to optionally compress the archive.
to compress a folder to .gz we use
tar cvzf backup.tgz /home/backups
-c creates archive
-v shows verbose
-z uses gzip compression
-f specify name of file
to extract a gzip encode file in current directory
tar -xvzf backup.tar.gz
to untar in a specific directory we use
tar -xvf backup.tar.gz -C /home/public_html/backups/