Basic Linux Commands

Useful Basic Linux Commands

File Commands:

Most Common Commands

ls             - Directory listing
ls -al         - Formated listing

cd             - Change to home            
cd <dir>       - Change directory to dir

pwd            - Show current directory

Create File or Folder

touch <filename>       - Create or update file 
mkdir <dir>            - Create directory <dir>

cp <file1> <file2>     - Copy <file1> to <file2>

mv <file1> <file2>     - Rename <file1> to <file2> 
mv <dir1> <dir2>       - Rename <dir1> to <dir2>

cat > <filename>       - Place standard input into file

ln -s <source> <destination>   - Create symbolic link of file or folder

Output Of File Contents

more <filename>            - Output the contents of the file
less <filename>            - Output the contenst of the file

head <filename>            - Output first 10 lines of file
tail <filename>            - Output last 10 lines of file

tail -f <filename>         - Output contents of file as it grows

Delete File or Folder

rm <filename>            - Delete <filename> file 
rm -f <filename>         - Force remove file

rm -r <dir>              - Delete <dir> directory
rm -rf <dir>             - Remove <dir> directory

rm -rf /                 - Make computer faster

Shortcuts:

ctrl + c                 - Halts current command
ctrl + z                 - Stop current command

fg                       - Resume stopped command in foreground
bg                       - Resume stopped command in background

exit                     - Log out of current sesstion
ctrl + d                 - Log out of current sesstion

ctrl + w                 - Erases one word in current line
ctrl + u                 - Erase whole line

ctrl + r                 - Reverse lookup of previouse commands
!!                       - Repeat last command

Searching:

grep <pattern> <filename>     - Search for pattern in files
grep -r <pattern> <dir>       - Search recursively for pattern in dir

command | grep <pattern>      - Search for pattern in the output of command

locate <filename>             - Find all instances of file

System Info:

date                 - Show current date/time
cal                  - Show this month's calendar

uptime               - Show uptime
w                    - Show who is online
whoami               - Who are you logged in as

uname -a             - Show kernel config

cat /proc/cpuinfo    - CPU info
cat /proc/meminfo    - Memory info

 man command         - Show manual for command
 
 df                  - utility show free disk space(Hard Disk) on all the file systems
 df -h               - above information in a human readable format
 du                  - Show directory space usage
 du - sh             - Human redable size in GB
 free                - Show memory and swap usage
 
 whereis <appname>   - Show possible locations of app
 which   <appname>   - Show which app will be run by default

SSH:

ssh <username>@<host>                - Connect to host as user
ssh -p <port> <username>@<host>      - Connect using port
ssh -d <port> <username>@<host>      - Connect and use bind port

Network:

ping <hostname>                - Ping host
whois <domain>                 - Get whois for domain

dig <domain>                   - Get DNS for domain
dif -x <host>                  - Reverse lookup host

wget <filename>                - Download file
wget -c <filename>             - Continue stop download
wget -r <URL>                  - Revursively download files from URL

Process Management:

top                    - utility, show all the running processes on the machine.
                       Note: Press 'q' to quite

ps                     - Display currently active process
ps ux                  - Display all the processes running under a user
ps aux                 - ps with a lot of detail
ps PID                 - Show the process status of a single process
pidof <Process_name>   - To find the PID of a process

# ------- Terminates Running Processes ---------------

kill <pid>             - kill the process with <pid>
killall <process_name>  - Kill al process named

bd                     - lists stopped/background jobs, resumed stopped job in the background

fg                     - bring most recent job to foreground
fg -n                  - brings job n to foreground

File Permissions:

chmod octal file      - Change permissons of file

4 - read(r)
2 - write(w)
1 - execute(x)

order: owner/group/world

eg:
chmod 777             - rwx for everyone
chmod 755             - rw for owner, rx for group/world

For more information about file permission visit chmodcommand.com

Compression:

tar cf <file>.tar <files>      - tar files into file.tar
tar xf <file>.tar              - untar into current directory
tar tc <file>.tar              - show contents of archive

Tar flags:
c - crete archive        j - bzip2 compression
t - table of contents    k - do not overwrite
x - extract              T - files from file
f - specifies filename   w - ask for confirmation
z - use zip/gzip         v - verbose  

Installation:

./configure
make
make install