A typical shell command might look like this:
$ ls -al ~/Downloads/
Let’s analyze the above. A command issued follows this pattern:
$ command -options argumentsFrom https://community.linuxmint.com/tutorial/view/244
date – Show the current date and time
cal – Show this month's calendar
uptime – Show current uptime
w – Display who is online
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
df -h – Show disk usage
du – Show directory space usage
free – Show memory and swap usage
Enter – Run the command
Up Arrow – Show the previous command
Ctrl + R – Allows you to type a part of the command
you're looking for and finds it
Ctrl + Z – Stops the current command, resume with
fg in the foreground or bg in the
background
Ctrl + C – Halts the current command, cancel the
current operation and/or start with a fresh new line
Ctrl + L – Clear the screen
command | less – Allows the scrolling of
the bash command window using Shift + Up Arrow and
Shift + Down Arrow
!! – Repeats the last command
command !$ – Repeats the
last argument of the previous command
Esc + . (a period) – Insert the last argument of the
previous command on the fly, which enables you to edit it before
executing the command
Ctrl + A – Return to the start of the command you're
typing
Ctrl + E – Go to the end of the command you're
typing
Ctrl + U – Cut everything before the cursor to a
special clipboard, erases the whole line
Ctrl + K – Cut everything after the cursor to a special
clipboard
Ctrl + Y – Paste from the special clipboard that
Ctrl + U and Ctrl + K save their data
to
Ctrl + T – Swap the two characters before the cursor
(you can actually use this to transport a character from the left to the
right, try it!)
Ctrl + W – Delete the word / argument left of the
cursor in the current line
Ctrl + D – Log out of current session, similar to exit
apropos subject – List
manual pages for subject
man -k keyword – Display man pages containing
keyword
man command – Show the manual for
command
man -t man | ps2pdf - > man.pdf –
Make a pdf of a manual page
which command – Show full
path name of command
time command – See how long a
command takes
whereis app – Show possible locations of
app
which app – Show which
app will be run by default; it shows the full
path
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 of
command
locate file – Find all instances of
file
find / -name filename – Starting with the root
directory, look for the file called
filename
find / -name ”*filename*” – Starting with the
root directory, look for the file containing the string
filename
locate filename – Find a file called
filename using the locate command; this
assumes you have already used the command updatedb (see
next)
updatedb – Create or update the database of files on
all file systems attached to the Linux root directory
which filename – Show the subdirectory
containing the executable file called
filename
grep TextStringToFind /dir – Starting
with the directory called dir, look for and
list all files containing TextStringToFind
chmod octal file – Change the
permissions of file to
octal, which can be found separately for user,
group, and world by adding: 4 – read (r), 2 – write (w), 1 – execute
(x)
Examples:
chmod 777 filename – read, write, execute for all
chmod 755 filename – rwx for owner, rx for group and
world
chmod symbolic file – You can also
change permissions in symbolic mode.
Examples:
chmod ugo+x filename – to make a file executable
chmod g+w filename – to grant write access to the
group
chmod o-r filename – to remove read access to
others
u: user
g: group
o: othersr: read
w: write
x: executable-R: recursivelyFor more options, see man chmod.
chown – change ownership
chown name_of_new_owner
filename
chown newuser:newgroup filename – To change ownership
of a file to newuser and the group
newgroup
chown root:www-data /var/www/html/ – To change
ownership of a file to root and the group
www-data
Check the current ownership of a file with: ls
-l
Check which groups you are in with: groups
ls – Directory listing
ls -l – List files in current directory using long
format
ls -laC – List all files in current directory in long
format and display in columns
ls -F – List files in current directory and indicate
the file type
ls -al – Formatted listing with hidden files
cd dir – Change directory to
dir
cd – Change to home
mkdir dir – Create a
directory dir
pwd – Show current directory
rm name – Remove a file or directory called
name
rm -r dir – Delete directory
dir
rm -f file – Force remove
file
rm -rf dir – Force remove an entire directory
dir and all it’s included files and
subdirectories (use with extreme caution)
cp file1 file2 – Copy
file1 to file2
cp -r dir1 dir2 – Copy
dir1 to dir2; create
dir2 if it doesn't exist
cp file /home/dirname – Copy the
filename called file to the
/home/dirname directory
mv file /home/dirname – Move the
file called filename to the
/home/dirname directory
mv file1 file2 – Rename or
move file1 to file2;
if file2 is an existing directory, moves
file1 into directory
file2
ln -s file link – Create symbolic link
link to file
touch file – Create or update
file
cat > file – Places standard input into
file
cat file – Display the file called
file
more file – Display the file called
file one page at a time, proceed to next page
using the spacebar
head file – Output the first 10 lines of
file
head -20 file – Display the first 20 lines of
the file called file
tail file – Output the last 10 lines of
file
tail -20 file – Display the last 20 lines of
the file called file
tail -f file – Output the contents of
file as it grows, starting with the last 10
lines
tar cf file.tar files ' – Create a
tar named file.tar containing
files
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 a 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
/etc/rc.d/init.d/lpd start – Start the print
daemon
/etc/rc.d/init.d/lpd stop – Stop the print daemon
/etc/rc.d/init.d/lpd status – Display status of the
print daemon
lpq – Display jobs in print queue
lprm – Remove jobs from queue
lpr – Print a file
lpc – Printer control tool
man subject | lpr – Print the manual page
called subject as plain text
man -t subject | lpr – Print the manual page
called subject as Postscript output
printtool – Start X printer setup interface
ifconfig – List IP addresses for all devices on the
local machine
iwconfig – Used to set the parameters of the network
interface which are specific to the wireless operation (for example: the
frequency)
iwlist – used to display some additional information
from a wireless network interface that is not displayed by
iwconfig
ping host – Ping
host and output results
whois domain – Get whois information for
domain
dig domain – Get DNS information for
domain
dig -x host – Reverse lookup
host
wget file – Download
file
wget -c file – Continue a
stopped download
ssh user@host – Connect to
host as user
ssh -p port user@host – Connect to
host on port port as
user
ssh-copy-id user@host – Add your key
to host for user to
enable a keyed or passwordless login
adduser accountname –
Create a new user call accountname
passwd accountname – Give
accountname a new password
su – Log in as superuser from current login
exit – Stop being superuser and revert to normal
user
ps – Display your currently active processes
top – Display all running processes
kill pid – Kill process id
pid
killall proc – Kill all processes named
proc (use with extreme caution)
bg – Lists 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
./configure
make
make install
dpkg -i pkg.deb – install a
DEB package (Debian / Ubuntu / Linux Mint)
rpm -Uvh pkg.rpm – install a RPM package (Red
Hat / Fedora)
shutdown -h now – Shutdown the system now and do not
reboot
halt – Stop all processes - same as above
shutdown -r 5 – Shutdown the system in 5 minutes and
reboot
shutdown -r now – Shutdown the system now and
reboot
reboot – Stop all processes and then reboot - same as
above
startx – Start the X system
Meta Characters are characters that have special meaning within the terminal
~ the tilde stands for the user's
home. cd ~/ change directory to home/ a single forward slash stands for
root. cd / change directory to root. dot stands for this directory.
ls . list this directory.. dot dot stands for the parent
directory to this directory. cp myfile.jpg .. copy
myfile.jpg to the parent directory* asterisk is a wildcards which represents zero or more
characters ls P*.jpg will list all the files, in the
current directory, that begin with P and end with .jpg\ backslash it is a literal character. It escape the
meta value of the meta-characters and display them only as literal
characters. echo Foo \* will output Foo * If \
wasn't there it would output all the files in that directory.man pages are manuals of program. They tells you what the program is, what it can do and how.
man df show the manual for the program
df that is used to display the free disk space
Can you find out how to display the output from df in a human readable format?
A pipes (" | ") sends the output of one program to the input of another program.
echo "my sentence"| wc the echoed sentence "my sentence"
is pipped into the program wc which counts the number of lines,
words, and characters
> Writes the output of a command to a file, rather
than to print on terminal.
df > df_output.txt redirect the content of
man dfM to a file called df_output.txt
If the said file doesn't exit it will create it, if it already exists it will overwrite its contents/
>> appends the output of a command to a file,
without overwriting the original file.
echo 'also add this' >> df_output.txt will add
'also add this' to the contents of df_output.txt
Package managers like apt-get and aptitude
(on Debian/Ubuntu Linux distributions) and Homebrew and MacPorts on Mac,
allow more (command-line, but not only) programs, than the ones that
come with the operating, to be installed on our system.