Cheatography
https://cheatography.com
A cheat sheet of the commands and hints I use most for Linux
Expansion
ls $(which cp)
ls `which cp`
|
Command expansion |
mkdir {2017...2020}-{01-12}
|
Brace expansion |
echo text ~/*.txt {a,b} $USER
|
Variable expansion |
echo "text ~/*.txt {a,b} $USER"
|
" expansion |
echo 'text ~/*.txt {a,b} $USER'
|
' expansion (NONE) |
Redirection & Commands
ls > file.txt
|
Standard Out |
ls 2> file.txt
|
Standard Error |
ls > file.txt 2>&1
ls &> file.txt
|
Standard Out & Error |
ls | tee file | wc -l
|
Read stdin & writes stdout |
cmd1 ; cmd2
|
Run cmd1 then cmd2 |
cmd1 && cmd2
|
Run cmd2 if cmd1 is OK |
cmd1 || cmd2
|
Run cmd2 if cmd1 is KO |
su / sudo
|
su [-[l]] [user]
Become another user, ROOT by default. If - or -l, load user envs and working dir.
|
|
su [user] -c 'command'
Execute command as user. Default root
|
|
sudo [-u user] command
Execute command as user. Default root
|
|
sudo -ll
Which commands I'm allowed to execute
|
|
visudo
Edit /etc/sudoers file. Example
teralco ALL=(root) NOPASSWD: /etc/init.d/jboss
teralco ALL=(jboss) NOPASSWD: /bin/kill
|
UFW
|
ufw status [verbose|numbered]
Show status and rules
|
|
ufw default deny incoming
ufw default allow outgoing
Deny all incoming traffic by default
Allow all outgoing traffic by default
|
|
ufw [allow|deny] from IP to [any|interface_name] [proto tcp|udp] port PORT
Full allow/deny rule
|
|
ufw [allow|deny] service_name
Allow/deny a service (ssh www ftp ...)
|
|
ufw [enable|disable]
|
|
ufw delete [rule|number]
|
|
|
Alt commands
|
/var/log/messages & /var/log/syslog
System log files
|
|
script file
Record session commands in file
|
|
nohup command &
Keep command running even after close session
|
|
tar -Jxvf file.tar.xz [-C dest_folder]
Extract xz (higher compress ratio)
|
|
zip -FF x.zip --out Y.zip && unzip Y.zip
Merge zip files (x.zip, x.z01, x.z02)
|
|
ps aux --sort -rss
Higher memory consumption processes
|
|
fdisk -l
List partition tables
|
|
dd bs=4M if=input.iso of=/dev/sd? conv=fdatasync
Burn iso in device
|
Searches
|
find path -name *.log -type f -mtime +5 -exec rm -rvf {} \;
Find and delete files older than 5 days
|
|
find path -type f -printf "%s\t%p\n" | sort -rn | head -10
Find the 10 biggest files
|
|
grep -rlie 'pattern' path
Find files with pattern content
|
|
du -cks path/* | sort -rn | head -10
Find biggest dirs
|
|
du -sh path
Dir size
|
Permissions
|
chmod [u|g|o][+|-|=][rwx] dir_file
Change permissions
|
|
chmod u[+|-]s file
Set uid. File is always exec as owner user
|
|
chmod g[+|-]s dir
Set gid. New files in folder are always owned by folder owner
|
|
chmod [+|-]t dir
Sticky Bit. Files in dir can only be renamed or removed by owner or root
|
|
umask xxxx
Set default permissions to dirs
|
|
|
Enviroment
/etc/profile
/etc/bash.bashrc
|
Global env config files |
~/.bashrc
~/.profile
|
User env config file |
printenv
|
Print defined env vars |
alias
|
Show defined aliases |
export VAR
|
Make a VAR available to child process |
source script
. script
|
Load a file into current script or shell session |
Network
|
ip addr
Show ips
|
|
ifup|ifdown interface_name
Up or down an interface
|
|
/etc/network/interfaces
File interfaces are defined
|
|
hostnamectl [set-hostname hostname]
Manage hostname (/etc/hostname) without restarting
|
|
netstat -tuln
All tcp and udp listening ports
|
|
ss -tuln
All tcp and udp listening ports
|
|
nc -vz host port
Scan port in host
|
SSH
|
ssh-keygen [-f /etc/ssh/ssh_host_rsa_key] -t rsa -b 4096
Generate ssh rsa key. By default ~/.ssh/id_rsa
|
|
ssh-copy-id [-i ~/.ssh/mykey] user@host
Copy ssh key in remote host (~/.ssh/authorized_keys). By default ~/.ssh/id_rsa.
|
|
ssh user@host command
Exec command in host
|
|
ssh -J hostA hostB
Connect to hostB through hostA (Jumping). Identification in localhost. Can use ProxyJump in ~/.ssh/config
|
|
ssh -D port -fCqN user@host
Proxy socket (HTTP and HTTPS traffic) through port.
|
|
ssh -nNT -L 9000:remote_server:80 user@host
Tunneling (Local port forwarding). Map remote_server:80 into localhost:9000 through host
|
|
ssh -nNT -R 9000:localhost:3000 user@host
Tunneling (Remote port forwarding). Map localhost:3000 into host:9000
|
|
Created By
Metadata
Comments
Nice, I will use it.
Add a Comment
Related Cheat Sheets