terminal cheatsheet
dir structure
| Directory | Description |
|---|---|
| bin | Essential command binaries. No subdirectories in /bin. |
| boot | Static files of the boot loader |
| dev | Device files |
| etc | Host-specific system configuration |
| lib | Essential shared libraries and kernel modules |
| media | Mount point for removeable media |
| mnt | Mount point for mounting a filesystem temporarily |
| opt | Add-on application software packages |
| sbin | Essential system binaries |
| srv | Data for services provided by this system |
| tmp | Temporary files |
| usr | Secondary hierarchy |
| var | Variable data |
Each directory listed above is specified in detail in separate subsections below.
/usr and /var each have a complete section in this document due to the complexity of those directories.
The following commands, or symbolic links to commands, are required in /bin.
Command Description cat Utility to concatenate files to standard output chgrp Utility to change file group ownership chmod Utility to change file access permissions chown Utility to change file owner and group cp Utility to copy files and directories date Utility to print or set the system data and time dd Utility to convert and copy a file df Utility to report filesystem disk space usage dmesg Utility to print or control the kernel message buffer echo Utility to display a line of text false Utility to do nothing, unsuccessfully hostname Utility to show or set the system's host name kill Utility to send signals to processes ln Utility to make links between files login Utility to begin a session on the system ls Utility to list directory contents mkdir Utility to make directories mknod Utility to make block or character special files more Utility to page through text mount Utility to mount a filesystem mv Utility to move/rename files ps Utility to report process status pwd Utility to print name of current working directory rm Utility to remove files or directories rmdir Utility to remove empty directories sed The `sed' stream editor sh The Bourne command shell stty Utility to change and print terminal line settings su Utility to change user ID sync Utility to flush filesystem buffers true Utility to do nothing, successfully umount Utility to unmount file systems uname Utility to print system information If /bin/sh is not a true Bourne shell, it must be a hard or symbolic link to the real shell command.
The [ and test commands must be placed together in either /bin or /usr/bin.
Tip Rationale
For example bash behaves differently when called as sh or bash. The use of a symbolic link also allows users to easily see that /bin/sh is not a true Bourne shell.
Specific Options The following programs, or symbolic links to programs, must be in /bin if the corresponding subsystem is installed:
Command Description csh The C shell (optional) ed The `ed' editor (optional) tar The tar archiving utility (optional) cpio The cpio archiving utility (optional) gzip The GNU compression utility (optional) gunzip The GNU uncompression utility (optional) zcat The GNU uncompression utility (optional) netstat The network statistics utility (optional) ping The ICMP network test utility (optional) If the gunzip and zcat programs exist, they must be symbolic or hard links to gzip. /bin/csh may be a symbolic link to /bin/tcsh or /usr/bin/tcsh.
Tip Rationale
The tar, gzip and cpio commands have been added to make restoration of a system possible (provided that / is intact).
Conversely, if no restoration from the root partition is ever expected, then these binaries might be omitted (e.g., a ROM chip root, mounting /usr through NFS). If restoration of a system is planned through the network, then ftp or tftp (along with everything necessary to get an ftp connection) must be available on the root partition.
Specific Options The following directories, or symbolic links to directories must be in /etc, if the corresponding subsystem is installed:
Directory Description opt Configuration for /opt The following files, or symbolic links to files, must be in /etc if the corresponding subsystem is installed: [6]
File Description csh.login Systemwide initialization file for C shell logins (optional) exports NFS filesystem access control list (optional) fstab Static information about filesystems (optional) ftpusers FTP daemon user access control list (optional) gateways File which lists gateways for routed (optional) gettydefs Speed and terminal settings used by getty (optional) group User group file (optional) host.conf Resolver configuration file (optional) hosts Static information about host names (optional) hosts.allow Host access file for TCP wrappers (optional) hosts.deny Host access file for TCP wrappers (optional) hosts.equiv List of trusted hosts for rlogin, rsh, rcp (optional) hosts.lpd List of trusted hosts for lpd (optional) inetd.conf Configuration file for inetd (optional) inittab Configuration file for init (optional) issue Pre-login message and identification file (optional) ld.so.conf List of extra directories to search for shared libraries (optional) motd Post-login message of the day file (optional) mtab Dynamic information about filesystems (optional) mtools.conf Configuration file for mtools (optional) networks Static information about network names (optional) passwd The password file (optional) printcap The lpd printer capability database (optional) profile Systemwide initialization file for sh shell logins (optional) protocols IP protocol listing (optional) resolv.conf Resolver configuration file (optional) rpc RPC protocol listing (optional) securetty TTY access control for root login (optional) services Port names for network services (optional) shells Pathnames of valid login shells (optional) syslog.conf Configuration file for syslogd (optional) mtab does not fit the static nature of /etc: it is excepted for historical reasons. [7]
go to homedir
getting manual
domain
apps
sudo ## if sudo doesnt exist
ipcalc ## calculate ip net
tree ## print dir structure
btop ## monitor
whois ## who is ?
perf ## speedtest generator
deja-dup ## simple backup
parted ## disk util
gparted ## disk util
screenfetch ## show info
screenfetch -n
tweaks ## system util gui
nautilus ## file manager gui
lastlog ## show last user
tldr ## show most useful commands for every package
curl
curl cheat.sh/<package> ## like tldr
insight
the -a option should be passed to see all files. by default tree does not print hidden files (those beginning with a dot ‘.’). In no event does tree print the file system constructs ‘.’ (current directory) and ‘..’ (previous directory).
to list directories only
random stuff
to get su
show user
screen
run command in background while closing ssh session
start a new named screen session
start a new daemon and log the output toscreenlog.x
show open screen sessions
reattach to an open screen
detach from inside a screen
kill the current screen session:
Ctrl + A, K
or
exit
history
Note
all inputs are logged in ~/.bash_history
delete history
change default history size 500 in ~/.bashrc
or run HISTSIZE=copy & paste in terminal
Note
sometimes just highlighting does copy the text or copy it with pressing scrollwheel
delete
delete folder and its files
umask
| Mask | Files | Directories |
|---|---|---|
| 000 | 666 (rw-rw-rw-) | 777 (rwxrwxrwx) |
| 002 | 664 (rw-rw-r--) | 775 (rwxrwxr-x) |
| 007 | 660 (rw-rw----) | 770 (rwxrwx---) |
| 022 | 644 (rw-r--r--) | 755 (rwxr-xr-x) |
| 027 | 640 (rw-r-----) | 750 (rwxr-x---) |
| 077 | 600 (rw-------) | 700 (rwx------) |
| 277 | 400 (r--------) | 500 (r-x------) |
permission
who own files
who has permission
sourceuser and groups
sudo passwd sudo su
user
getent passwd cat /etc/passwd
useradd -D useradd ## Manual guided adduser ## Automatic
group
getent group
less /etc/group
groups
show open ports
or
dmesg
kernel
show logs when its not directly kernel relevated show last boot messagesfollow logs