Linux Commands

Posted on Posted in Network Technology

File Commands:

ls – Directory listing

ls -al – formatted listing with hidden fies

cd dir – Change directory to dir

cd -change to home

pwd – show current diectory

mkdir dir – create directory file

rm – r dir – delete directory dir

rm -f file – forceremove file

rm -rf dir – remove directory file

cp file1 file 2 – copy file1 to file2

mv file1 file2 – move file1 to file2

ln -s file link – create symbolic link  “link” to file

touch file – create or update file

cat > file – plcase standard input into file

more file – output the contents of the file

less file – output the contents of the file

head file – output first 10 lines of file

tail file – output last 10 lines of file

tail -f file – output contents of file as it grows

SSH:

ssh user@host – connect to host as user

ssh -p port user@host – connect using port p

ssh -D port user@host – connect and use bind port

Installation:

./configure

make

make install

NETWORK:

ping host – ping host ‘host’

whois domain – get whois for domain

dig domain – get DNS for domain

dig -x host – reverse lookup host

wget file – download file

wget -c file – continue stopped download

wget -r url – recursively download files from url

SYSTEM INFO:

date – show current date/time

cal – show this month’s calendar

upptime – show uptime

-w – display who is online

whoami – who are you logged in as

unmae -a – show kernel config

cat /proc/cpuinfo – cpu info

cat /proc/meminfo – memory information

df – show disk usage

du – show directory space usage

du -sh – human readable size in GB

free – show memory and swap usage

whereis app – show which app will be running by default

SEARCHING:

grep pattern files – search for pattern in files

grep -r pattern dir – search recursively for pattern in dir

command | grep pattern – search for pattern in the output command

locate file – find all instances of file

PROCESS MANAGEMENT:

ps – display currently active processes

ps aux – ps with lot of detail

kill pid – kill process pid ‘pid’

killall proc – kill all processes named proc

bg – lists stopped/background jobs, resume stopped job in the bacground

fg n  – brings job n to foreground

FILE PERMISSIONS:

chmod octal file – change permission 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

COMPRESSION:

tar flags:

c- create archive            j – bzip2 compression

t – table of contents      k – do not overwrite

x – extract                      T – files from file

f – specific filename    w- ask for confirmation

z- use zip/gzip             v- verbose

gzip file – compress file and rename to file.gz

SHORTCUTS:

ctrl+c – halts current command

ctrl+z – stops current command

fg – resume stopped command in foreground

bg – resume stopped command in backgound

ctrl+d – log out of current session

ctrl+w – erases one word in current line

ctrl+u – erases whole line

ctrl+r – reverse lookup pf previous commands

!! – repeat last command

exit – log out of current session

 

 

 

 

 

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