Cheatography
https://cheatography.com
A cheat sheet of the commands and hints I use most for Linux
Expansionls $(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 & Commandsls > 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 / sudosu [-[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 |
UFWufw 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]
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| | 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 |
Searchesfind 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 |
Permissionschmod [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 |
Networkip 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 |
SSHssh-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 |
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Comments
Nice, I will use it.
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