Linux Commands

Linux Commands

ls

Directory Listing

ls -al

Formatted Listing with hidden files

ls -lt

Sorting the Formatted listing by modification

cd dir

Change directory to dir

cd

Change to home directory

pwd

Show current working directory

mkdir dir

Creating a directory dir

cat > file

Places the standard input into the file

more file

Output the contents of the file

head file

Output the first 10 lines of the file

tail file

Output the last 10 lines of the file

tail -f file

Output the contents of file as it grows, starting with the last 10 lines

touch file

Create or update file

rm file

Deleting the file

rm -r dir

Deleting the directory

rm -r file

Force to remove the file

rm -rf dir

Force to remove the directory dir

cp file1 file2

Copy the contents of file1 to file2

cp -r dir1 dir2

Copy dir1 to dir2;create dir2 if not present

mv file1 file2

Rename or move file1 to file2,if file2 is an existing directory

ln -s file link

Create symbolic link link to file

ps

To display the currently working processes

top

Display all running process

kill pid

Kill the process with given pid

killall proc

Kill all the process named proc

pkill pattern

Will kill all processes matching the pattern

bg

List stopped or background jobs, resume a stopped job in the background

fg

Brings the most recent job to foreground

fg n

Brings job n to the foreground

chmod octal file

Change the permission of file to octal, which can be found separately for user, group, world by adding,

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

grep pattern file

Search for pattern in file

grep -r pattern dir

Search recursively for pattern in dir

command | grep pattern

Search pattern in the output of a command

locate file

Find all instances of file

find . -name filename

Searches in the current directory (represented by a period) and below it, for files and directories with names starting with filename

pgrep pattern

Searches for all the named processes , that matches with the pattern and, by default, returns their ID

date

Show the current date and time

cal

Show this month's calendar

uptime

Show current uptime

w

Display who is on line

whoami

Who you are logged in as

finger user

Display information about user

uname -a

Show kernel information

cat /proc/cpuinfo

Cpu information

cat proc/meminfo

Memory information

man command

Show the manual for command

df

Show the disk usage

du

Show directory space usage

free

Show memory and swap usage

whereis app

Show possible locations of app

which app

Show which applications will be run by default

tar cf file.tar file

Create tar named file.tar containing file

tar xf file.tar

Extract the files from file.tar

tar czf file.tar.gz files

Create a tar with Gzip compression

tar xzf file.tar.gz

Extract a tar using Gzip

tar cjf file.tar.bz2

Create tar with Bzip2 compression

tar xjf file.tar.bz2

Extract a tar using Bzip2

gzip file

Compresses file and renames it to file.gz

gzip -d file.gz

Decompresses file.gz back to file

ping host

Ping host and output results

whois domain

Get whois information for domains

dig domain

Get DNS information for domain

dig -x host

Reverse lookup host

wget file

Download file

wget -c file

Continue a stopped download

ctrl+c

Halts the current command

ctrl+z

Stops the current command, resume with fg in the foreground or bg in the background

ctrl+d

Logout the current session, similar to exit

ctrl+w

Erases one word in the current line

ctrl+u

Erases the whole line

ctrl+r

Type to bring up a recent command

!!

Repeats the last command

exit

Logout the current session