All Commands

This document contains all the commands used in the TCM Academy course "Linux 101." It is provided as a supplement to the videos for convenience. The course videos provide context and commentary for these commands that are necessary for your mastery of the topics. Note that only significant commands are present. Commands such as "clear" are not listed.

Getting Started

Intro to the Command Line

whoami
Whoami
hostname
pwd
ls
cd files
cd ..

Getting Help on the Command Line

man ls
info ls
ls --help

Command Line Arguments and Options

man ls
ls -al
ls --all -l
man ls
ls
ls -I "file*"
ls --ignore="file*"

Looking at Text Files: more and less

ls
more wordlist.txt
less wordlist.txt
more image.jpg

Another Way to Look at Text Files: cat

man cat
ls
cat file1.txt
cat file3.txt
cat file1.txt file3.txt
cat file3.txt file1.txt
cat
Hello world
man cat
cat -b file3.txt file1.txt
cat -n file3.txt file1.txt
cat file3.txt file1.txt > combined.txt
cat combined.txt
cat > new-file.txt
Hello world
Ctrl+D
cat new-file.txt

Files and Filesystems

Linux Filesystem Hierarchy Standard

man hier

Devices, Partitions, and Mounting

mount
df -h
du -sh ~

Absolute and Relative Paths

ls /home/bob/files/notes.txt
cd /var/log
ls /home/bob/files/notes.txt
ls /home/bob/files/no-such-file.txt
cd /home/bob
ls files/notes.txt
ls ./files/notes.txt
cd files
ls notes.txt
ls ./notes.txt
cd ../backup
ls ../files/notes.txt
cd /var/log
ls ../../home/bob/files/notes.txt

Working with Files and Directories

ls -l notes.txt
touch notes.txt
ls -l notes.txt
touch test.txt
ls test.txt
cp notes.txt notes-copy.txt
man cp
mv notes-copy.txt ../backup/
ls ../backup
rm ../backup/notes-copy.txt
ls ../backup
man rm
mkdir project
cd project
cd ..
rmdir project
ls non-empty-dir/
rmdir non-empty-dir
rm -rf non-empty-dir
mkdir project
mv project project01

Spaces in Paths and Filenames

cd spaces
ls
cat file name.txt
cd my dir
cat file\ name.txt
cd my\ dir
cd ..
cat "file name.txt"

File and Path Expansion

ls file*.txt
ls file?.txt
ls **/*.txt
shopt -s globstar
ls file[123].txt
ls file[1-3].txt
ls file[a-zA-Z].txt

More Looking at Text Files: head, tail, and diff

head wordlist.txt
head -n 5 wordlist.txt
head -5 wordlist.txt
tail wordlist
tail -n 5 wordlist.txt
tail -5 wordlist.txt
tail -f /var/log/auth.log
<in another terminal> sudo ls
diff file1.txt file3.txt
Hard and Soft Filesystem Links
cat hello.txt
ln hello.txt hello-hard-link.txt
<edit hello.txt>
cat hello.txt
cat hello-hard-link.txt
ls -l hello*.txt
rm hello.txt
cat hello-hard-link.txt
ln hello-hard-link.txt hello.txt
ln -s ./hello.txt hello-soft-link.txt
ls -l hello*.txt

Compressing and Archiving Files

man zip
zip tmp/backup-files.zip file1.txt file2.txt file3.txt
ls tmp
unzip -l tmp/backup-files.zip
ls dir1 dir2
zip tmp/backup-dirs.zip dir1 dir2
unzip -l tmp/backup-dirs.zip
rm tmp/backup-dirs.zip
zip -r tmp/backup-dirs.zip dir1 dir2
unzip -l tmp/backup-dirs.zip
man tar
tar cvf backup.tar file?.txt dir? shakespeare.txt
tar tvf backup.tar
cd test
tar xvf ../backup.tar
ls
ls dir?
rm -rf *
cd ..
ls -lh backup.tar
gzip backup.tar
ls -lh backup.tar.gz
gunzip backup.tar.gz
ls
tar cvfz backup2.tar.gz file?.txt dir?
ls -l backup2.tar.gz

Searching the Filesystem

man find
find . -name 'file*.txt'
find . -iname 'file*.txt'
locate file.txt
locate file*.txt
locate -i file*.txt
which ls

Users and Groups

Working with Users and Groups

users
who
w
less /etc/passwd
less /etc/group
ls -la /home

File and Directory Permissions

ls -l
man chmod
ls -l hello.txt
chmod g-w hello.txt
ls -l hello.txt
chmod a=,u=r hello.txt
ls -l hello.txt
chmod 664 hello.txt
ls -l hello.txt
man chown
ls -l hello.txt
chown sally hello.txt
ls -l hello.txt
chgrp sally hello.txt
ls -l hello.txt

Changing Users

cat /etc/shadow
sudo cat /etc/shadow
cat /home/sally/sample.txt
ll /home/sally/sample.txt
sudo -u sally cat /home/sally/sample.txt
su sally

Changing Passwords

man passwd
passwd
<enter wrong password>
passwd
sudo passwd sally

Installing Software

Package Management: Debian Systems

man dpkg
apt update
apt list --upgradable
apt upgrade
which pdftk
apt search pdftk
apt show pdftk
apt install pdftk-java
which pdftk
apt remove pdftk-java
apt purge pdftk-java
apt autoremove

Package Management: RedHat Systems

sudo yum check-update
sudo yum update
yum search qpdf
yum info qpdf
sudo yum install qpdf
which qpdf
yum remove qpdf

Manually Installing Software

apt install build-essential automake checkinstall libz-dev libssl-dev libcurl4-gnutls-dev libexpat1-dev gettext cmake gcc curl
which git
cd Downloads
wget https://mirrors.edge.kernel.org/pub/software/scm/git/git-2.29.3.tar.gz
tar xfz git-2.29.3.tar.gz
ls
cd git-2.29.3/
less INSTALL
./configure
make
sudo make install
git --version

Shells

Environment Variables

printenv | less -S
COUNT_LOCAL=42
echo $COUNT_LOCAL
echo COUNT_LOCAL
bash
echo $COUNT_LOCAL
exit
echo $COUNT_LOCAL
export COUNT_GLOBAL=55
echo $COUNT_GLOBAL
bash
echo $COUNT_GLOBAL
exit
unset COUNT_GLOBAL
echo $COUNT_GLOBAL

Startup Files

ls -al ~
nano .bashrc
<Add lines>
alias del='rm -rfi'
alias c='clear'
<Save and exit>
c
<new shell>
ls
c
<original shell>
source .bashrc
c

Redirecting Input and Output

sudo ls /root
ls /root
ls /etc/
ls /etc/ > ~/dir-contents.txt
less ~/dir-contents.txt
ls /tmp/
ls /tmp/ > ~/dir-contents.txt
less ~/dir-contents.txt
ls /etc/ >> ~/dir-contents.txt
less ~/dir-contents.txt
clear
head /etc/passwd
head < /etc/passwd
clear
find / -name 'sample.txt'
find / -name 'sample.txt' 2> errors.txt
less errors.txt
find / -name 'sample.txt' 2> /dev/null
cat /dev/null
find / -name 'sample.txt' &> all.txt
less all.txt
find / -name 'sample.txt' > all.txt 2>&1
find / -name 'sample.txt' > location.txt 2> /dev/null
cat location.txt

Pipes

ls -l /etc/ | less
ls -l /etc/ | head -n 20 | tail -n 5
find / -name 'sample.txt' | less
find / -name 'sample.txt' |& less

Command History

history
history | tail
!<insert command #>
!10
!-1
!!
!cat
cat file1.txt
^file1.txt^fileA.txt^
history
less ~/.bashrc

Command Substitution

cat file-list.txt
cat file-list.txt | ls -l
ls -l < file-list.txt
ls -l `cat file-list.txt`
ls -l cat file-list.txt
ls -l $(cat file-list.txt)

More Utilities

Searching and Processing Text

man grep
grep bob wordlist.txt
grep -v e wordlist.txt | less
grep error /var/log/*.log
grep error -A 1 -B 3 /var/log/*.log
cat random-words.txt
sort random-words.txt
cat random-numbers.txt
sort -nr random-numbers.txt
man uniq
less random-words.txt
uniq random-words.txt
sort duplicates.txt | uniq
wc wordlist.txt
grep bob wordlist.txt | wc -l
clear
grep -v e random-words.txt
grep -v e random-words.txt | sort
grep -v e random-words.txt | sort | uniq
grep -v e random-words.txt | sort | uniq | wc -l

Manipulating Text

man sed
cat sample.txt
sed 's/Suite/Ste/' sample.txt
echo Suite Suite | sed 's/Suite/Ste/'
echo Suite Suite | sed 's/Suite/Ste/g'
sed '$s/Suite/Ste/g' sample.txt
sed '/Suite/d' sample.txt
grep Suite sample.txt
sed '/ee/ s/Suite/Ste/g' sample.txt
sed 's/$/\n/g' sample.txt | sed 's/,/\n/g'
sed -e 's/$/\n/g' -e 's/,/\n/g' sample.txt
clear
echo linux bob sally | awk '{print $2}'
echo linux bob sally | awk '{print $3,"likes",$1}'
awk -F ',' '{print $1}' sample.txt
awk -F ',' '{print $1}' sample.txt | awk '{print $2 ", " $1}'
cat sample.txt
awk -F ',' '/Dakota/ {print $1}' sample.txt
awk -F ',' '/Dakota/ {print NR,$1}' sample.txt
cat sample.txt | tr ',' '\t'
cat sample.txt | tr 'a-z' 'A-Z'
man tr
cat sample.txt | tr '[:lower:]' '[:upper:]'

Networking at the Command Line

ping google.com
ping -c 3 google.com
ifconfig
man ifconfig
ip address
ip -s link
ip help
ip address help
ip link help
ip address
sudo ip link set dev enp0s3 down
ip address
ping google.com
sudo ip link set dev enp0s3 up
ip address
ping google.com
ip route
route
sudo ip route add 10.0.3.0/24 via 10.0.2.1
ip route
sudo ip route delete 10.0.3.0/24 via 10.0.2.1
ip route
nslookup google.com
dig google.om
dig -x 8.8.8.8
netstat -at
netstat -at
netstat -lt
Type in separate terminal: python3 -m http.server
netstat -lt

File Transfer Utilities

scp file.txt 192.168.100.4:/home/bob/
Remote host: ls
scp -r files 192.168.100.4:/home/bob/
Remote host: ls
Remote host: ls files/
scp 192.168.100.4:/home/bob/remote-file.txt backup/
scp -r 192.168.100.4:/home/bob/remote-files backup/
scp file.txt sally@<ip>:/home/sally/
rsync -avzh file2.txt 192.168.100.4:/home/bob/
rsync -avzh file2.txt 192.168.100.4:/home/bob/
man rsync

Converting Text Files

cd line-endings
ls
file *.txt
vim sample-dos-file.txt
:e ++ff=unix
vim sample-macos-file.txt
cp sample-unix-file.txt temp.txt
unix2dos temp.txt
file temp.txt
unix2dos -n sample-unix-file.txt temp.txt
file temp.txt
cp sample-unix-file.txt temp.txt
unix2dos -c mac temp.txt
file temp.txt
cp sample-dos-file.txt temp.txt
dos2unix temp.txt
file temp.txt
cp sample-macos-file.txt temp.txt
dos2unix -c mac temp.txt
file temp.txt

Process Management

Process Information

ps
man ps
ps ax | less -S
ps -e | less -S <separate window>
ps aux | less -S
ps -ef | less -S
man ps
ps -U root -u root u | less -S
ps -eH | less -S
pstree | less -S
top
d

Foreground and Background Processes

xeyes
ls
Ctrl+c
xeyes &
ls
xeyes
Ctrl+Z
jobs
bg
jobs
fg
ls
xclock &
jobs
fg 2
Managing Processes
man kill
kill -l
xeyes &
ps -ef | grep xeyes
kill <PID>
xeyes &
ps -ef | grep xeyes
kill -9 <PID>
man pkill
xeyes &
xeyes &
pkill xeyes
sleep 10

Scheduling Processes with Crontab

less /etc/crontab
ll /etc/cron.daily
crontab -e
5 1 2 * * touch /home/bob/cron/crontab-ran.txt
5 1,13 2 * * touch /home/bob/cron/crontab-ran.txt
*/5 * * * * touch /home/bob/cron/crontab-ran.txt
crontab -l
ll /home/bob/cron/crontab-ran.txt
ll /home/bob/cron/crontab-ran.txt
crontab -r
crontab -l
cd /etc/init.d
ls
ls -d /etc/rc*.d
ls -l /etc/rc5.d/

Regular Expressions

What is a Regular Expression?

^(?=[A-Z0-9][A-Z0-9@._%+-]{5,253}$)[A-Z0-9._%+-]{1,64}@(?:(?=[A-Z0-9-]{1,63}\.)[A-Z0-9]+(?:-[A-Z0-9]+)*\.){1,8}[A-Z]{2,63}$

^(?:[a-z0-9!#$%&'*+/=?^_`{|}~-]+(?:\.[a-z0-9!#$%&'*+/=?^_`{|}~-]+)*|"(?:[\x01-\x08\x0b\x0c\x0e-\x1f\x21\x23-\x5b\x5d-\x7f]|\\[\x01-\x09\x0b\x0c\x0e-\x7f])*")@(?:(?:[a-z0-9](?:[a-z0-9-]*[a-z0-9])?\.)+[a-z0-9](?:[a-z0-9-]*[a-z0-9])?|\[(?:(?:25[0-5]|2[0-4][0-9]|[01]?[0-9][0-9]?)\.){3}(?:25[0-5]|2[0-4][0-9]|[01]?[0-9][0-9]?|[a-z0-9-]*[a-z0-9]:(?:[\x01-\x08\x0b\x0c\x0e-\x1f\x21-\x5a\x53-\x7f]|\\[\x01-\x09\x0b\x0c\x0e-\x7f])+)\])$

https://www.ex-parrot.com/pdw/Mail-RFC822-Address.html

Searching with Regular Expressions

Links to regular expressions on Regexr:

https://regexr.com/66ogg
https://regexr.com/66ogj
https://regexr.com/66ogm
https://regexr.com/66ogv

Replacing with Regular Expressions