Rocky Linux
Last updated
Was this helpful?
Last updated
Was this helpful?
đ These are Linux commands notes taken from the Rocky Linux docs, maybe I'll move them to a more Linux general section later.
Treat everything as a file.
Value portability.
Do one thing and do it well.
KISS: Keep It Simple Stupid.
"UNIX is a simple operating system, but you have to be a genius to understand the simplicity." (Dennis Ritchie)
"Unix is user-friendly. It just isn't promiscuous about which users it's friendly with." (Steven King)
# command [option(s)] [argument(s)]
/bin/bash
cat /etc/passwd
cat /etc/shadow
cat /etc/profile
cat /etc/sudoers
apropos --exact password -a change
whatis clear
man clear
reboot
shutdown -r +5
shutdown now
shutdown -h 0:30
shutdown -h 0:30 "Server shutdown at 0:30"
shutdown --show
shutdown -c
history
clear
echo -ne "\t Hello \n"
echo $LANG
echo $PATH
date
date +%F
date +%x
date +%T
date -d 20250310 +%j
# Convert timestamp to a date
date -d "1970-01-01 20156 days"
# Convert date to timestamp
echo $(($(date --date="2025-01-25" +%s)/86400+1))
id root
whoami
who
who -r
pwd
cd
ls
ls -l
ls -ld
ls -lX
ls -g
ls -dl
ls -lah
ls -ltr
ls -lhS
ls -lhR
ls -liah
ls -lAhR
ls -lhR /var/ | grep ^\- | grep -E "[1-9]*\.[0-9]*M"
alias
ll
du -sh /etc
mkdir -p /tmp/newdir/newsubdir
touch file
touch -t [AAAA]MMJJhhmm[ss] file
rmdir /tmp/newdir/newsubdir
rm file
rm -r dir
rm -rf dir/files
rm -f -- -file
mv file1 file2
mv file1 file2 /tmp
cp file1 file2
cp file /tmp
cp -pr dir1 dir2
file /etc/passwd
more /etc/passwd
less file1
/text # search
g or G # first/last page
cat /etc/passwd
cat -n /etc/passwd
cat -b /etc/profile
cat /etc/passwd /etc/group
tac /var/log/messages | less
head -n 20 /etc/profile
tail -n 20 /etc/profile
tail -f /var/log/messages
sort -k 3,4 -t ":" -n /etc/passwd
sort -u FILE
sort FILE | uniq
sort -nr ips.txt
sort -hr size.txt
wc -c
wc -l
find /tmp -name *.txt -exec rm -f {} \;
find /tmp -name *.txt -delete
find /var -size +1M -a -size -1024M -a -type f -exec ls -lh {} \;
whereis ls
which ls
grep "root*" /etc/passwd
grep -w "root:" /etc/passwd
grep -w "^root" /etc/passwd
grep -i version /etc/os-release
grep -iv version /etc/os-release
grep -R "systemd" /var/log/# Input redirection
ftp -in serverftp << ftp-commands.txt
wc -l /etc/profile
wc -l < /etc/profile
# Output redirection
date +%F > date_file # overwrite
date +%F >> date_file # append
# stderr output redirection
ls -R / 2> errors_file
ls -R / >> ok_file 2>> nok_file
ls -R / >> log_file 2>&1
ls -R / 2>> /dev/null
# Copy stdin to file and to stdout
cat /etc/os-release | tee release
# Pipes
ls -lia / | head
ls -lia / | tail
ls -lia / | sort
ls -lia / | wc
ls -lia / | grep etc
ls -lia / | tee list
# Aliases
alias
cat .bashrc # permanent user's aliases file
cat /etc/bashrc # all users file
type ls
ls
\ls
mount | column -t
ls /; cd /home; ls -lia; cd /sort firstnames.txt | uniq
sort firstnames.txt | uniq -cd
xargs ls -ld
/home
/tmp
<CTRL+D>
xargs -L 1 find /var/log -name
xargs -n 1 find /var/log -name
find /var/log/ -name "*.log" -mtime -1 | xargs tar cvfP /root/log.tar
mkdir /tmp/backup && find /var/log -type f -name "*.log" | xargs -I % cp % /tmp/backup
watch
watch -n 5 tail -n 5 /var/log/secure
watch -n 1 'ls -l | wc -l'
watch -t -n 1 date
install -d /tmp/samples
install /tmp/test.txt /tmp/samples/
install -v -o syselement -g users -m 644 -D -t /tmp/samples/ /tmp/test.txt
install -v -b -S ".bak" -D -t /tmp/samples/ /tmp/test.txt
tree
tree -ah
tree -hugp /etc/security/
stat /var/log/messages# yum/dnf
# yum-utils / dnf-utils package
dnf install dnf-utils
repoquery
repoquery -l yum-utils
rpm -ql yum-utils # same
yumdownloader --destdir /var/tmp/ --resolve samba
dnf download --downloadonly --downloaddir /var/tmp --resolve samba # same
# pmisc package
pstree
killall nc
fuser# Files
/etc/passwd
/etc/shadow
/etc/group
/etc/gshadow
/etc/skel/
/etc/default/useradd
/etc/login.defs# Groups
cat /etc/group
cat /etc/gshadow
groupadd -g 1020 group1
# Debian
addgroup
groupmod -g 1022 group1
groupmod -n group3 group2
sudo find / -gid 1020 -exec chgrp 1022 {} \;
groupdel group1
# root GID = 0
gpasswd -a user2 group1
gpasswd -d user2 group1
echo $SHLVL ; echo $BASH_SUBSHELL
newgrp group1 # child shell with temp group1# Users
# root (uid=0) - system admin
# system users (uid=201~999)
# regulare users (uid>=1000)
cat /etc/passwd
cat /etc/shadow
# ! For each line in the /etc/passwd file there must be a corresponding line in the /etc/shadow file.
# default settings
ls -lah /etc/skel/ # file templates for new user home dir
cat /etc/login.defs
cat /etc/default/useradd
useradd -D # shows /etc/default/useradd contents
useradd user1 # defaults from /etc/default/useradd
useradd -N user1 # no user group, uses the default (users:100)
useradd -u 1002 -g 1020 -d /home/user user2
passwd user1
tail -n 2 /etc/passwd
tail -n 2 /etc/shadow
tail -n 2 /etc/group ; tail -n 2 /etc/gshadow
# Debian
adduser
deluser
usermod -u 1005 user1
usermod -L user2 # lock user
usermod -G user1 user2
userldel -r user1 # deletes user's home dir, mail files and primary group
# File owners
chown user1 file
chown :group1 file
chown user1:group1 file
chown -R -v user1:group1 /tmp/dir
chown --reference=./file2 file
chgrp group1 filepasswd
passwd user1
passwd -S user1
passwd -l user1 # lock user
passwd -u user1 # unlock user
sudo echo "p@ssw0rd" | passwd --stdin user1 # default pw, e.g. in scripts
chage user1
chage -m 60 -M 90 -W 80 -I 10 user1 # pw expire
su # login as root
su - user1
su - root -c "cat /etc/shadow"...Ctrl + A # Move to the start of the line.
Ctrl + E # Move to the end of the line.
Ctrl + U # Delete from the cursor to the start of the line.
Ctrl + K # Delete from the cursor to the end of the line.
Ctrl + W # Delete the word before the cursor.
Ctrl + L # Clear the terminal screen.
Ctrl + C # Stop the current process/command.
Ctrl + D # Log out or exit the terminal.
Ctrl + Z # Pause the current process (can be resumed).
Ctrl + R # Search command history (backward search).
Up Arrow # Show the previous command (from the command history).
Down Arrow # Show the next command (from the command history).
!! # Repeat the last command.
!n # Repeat the nth command from history.
Tab # Auto-complete commands, files, or directories.
Tab twice # List all possible completions.
Ctrl + Shift + C # Copy the selected text or command.
Ctrl + Shift + V # Paste copied text or command.
Ctrl + Shift + N # Open a new terminal window.
Ctrl + Shift + T # Open a new tab in the terminal.
Ctrl + Tab or Ctrl + PageDown # Switch between terminal tabs.vi
