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)
|
ls > file.txt |
Standard Out
|
ls 2> file.txt |
Standard Error
|
ls > file.txt 2>&1ls &> 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 [-[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 status [verbose|numbered]
Show status and rules
|
ufw default deny incomingufw 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] |
/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
|
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
|
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
|
/etc/profile |
Global env config files
|
/.bashrc |
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
|
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-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
|
Cheatography n. The art of mapping complex subjects into clear, instantly navigable reference guides.
