Special Characters
. - current directory
.. - up one directory
* - wildcard
# - comment character ignored by shell
~ - tilde expansion represents users /home directory
> - redirects output to a file (overwrites)
>> - redirects output to a file (appends)
| - pipe redirects output of one command as input to another
&& - runs a second command if the first one succeeds
!! - last command
|| - runs a second command if the first one fails
2> - redirects standard error to a file (overwrites)
2>> - redirects standard error to a file (appends)
&> - redirects standard output and error to a file (overwrites)
&>> - redirects standard output and error to a file (appends)
Shell Keyboard Shortcuts
The goal with these shortcuts is to avoid taking your hands off the home row.
Ctrl+r - search through command history
Ctrl+l - clears the screen
Ctrl+a - moves cursor to the beginning of the line
Ctrl+e - moves cursor to the end of the line
Ctrl+f - moves cursor one character to the right
Ctrl+b - moves cursor one character to the left
Ctrl+u - deletes everything before the cursor
Ctrl+w - deletes the word before the cursor
Ctrl+d - deletes the word after the cursor
Ctrl+z - suspends the current process
fg to resume process
Navigating the File System
pwd
pwd displays the current directory
╭─jacob@pop-os ~
╰─➤ pwd
/home/jacob
ls
ls lists the contents of the current directory
╭─jacob@pop-os ~/scratch
╰─➤ ls
example-folder example.txt
ls -lath useful flags to do a long list of all files sorted by time with human readable file sizes
╭─jacob@pop-os ~/scratch
╰─➤ ls -lath
total 12K
drwxr-x---+ 51 jacob jacob 4.0K Aug 20 18:55 ..
drwxrwxr-x 3 jacob jacob 4.0K Aug 20 18:53 .
drwxrwxr-x 2 jacob jacob 4.0K Aug 20 18:53 example-folder
-rw-rw-r-- 1 jacob jacob 0 Aug 20 18:52 example.txt
cd
cd /where/you/want/to/go command changes the directory
╭─jacob@pop-os ~
╰─➤ cd /
╭─jacob@pop-os /
╰─➤ pwd
/
cd ~ takes you to right to your home directory
cd .. moves you up a directory
Viewing File System Contents
cat
cat displays the contents of a file
╭─jacob@pop-os ~/scratch
╰─➤ cat example.txt
This is the text inside the file example.txt
less
less is more. That is a linux joke you might here old people say. less is inspired by the command more which let’s you look at the contents of files using your keyboard to navigate, but less has more features than more.
less /etc/services
q quits less
j moves down one line
k moves up one line
h opens the less help menu
Arrow keys work
Page up/down work
head
head prints the first 10 lines of a file by default
╭─jacob@pop-os ~/scratch
╰─➤ head /etc/services
# Network services, Internet style
#
# Updated from https://www.iana.org/assignments/service-names-port-numbers/service-names-port-numbers.xhtml .
#
# New ports will be added on request if they have been officially assigned
# by IANA and used in the real-world or are needed by a debian package.
# If you need a huge list of used numbers please install the nmap package.
tcpmux 1/tcp # TCP port service multiplexer
echo 7/tcp
head -n [number] prints the specified number of lines
tail
tail prints the last 10 lines of a file be default
╭─jacob@pop-os ~/scratch
╰─➤ tail /etc/services
sgi-cad 17004/tcp # Cluster Admin daemon
binkp 24554/tcp # binkp fidonet protocol
asp 27374/tcp # Address Search Protocol
asp 27374/udp
csync2 30865/tcp # cluster synchronization tool
dircproxy 57000/tcp # Detachable IRC Proxy
tfido 60177/tcp # fidonet EMSI over telnet
fido 60179/tcp # fidonet EMSI over TCP
# Local services
tail -n [number] prints the specified number of lines
tail -f displays data appended to file as it grows
file
file determines type of file and provides useful information about the file. file doesn’t just look at the file extension, but inspects the contents and can reveal some useful information.
╭─jacob@pop-os ~/scratch
╰─➤ file /etc/services
/etc/services: ASCII text
╭─jacob@pop-os ~/scratch
╰─➤ file /dev/sda
/dev/sda: block special (8/0)
╭─jacob@pop-os ~/scratch
╰─➤ file /usr/bin/pip
/usr/bin/pip: Python script, ASCII text executable
╭─jacob@pop-os ~/scratch
╰─➤ file ~/Pictures/10-08-23-hiking-mt-biersdat/DSCF0503.JPG
/home/jacob/Pictures/10-08-23-hiking-mt-biersdat/DSCF0503.JPG: JPEG image data, Exif standard: [TIFF image data, little-endian, direntries=13, manufacturer=FUJIFILM, model=X-T30 II, orientation=upper-left, xresolution=190, yresolution=198, resolutionunit=2, software=Digital Camera X-T30 II Ver1.20, datetime=2023:10:07 08:39:09], baseline, precision 8, 4416x2944, components 3
du
df
Directory and File Management
mkdir
rmdir
rm
touch
cp
mv
mv [file] [destination] command
