Linux Cheatsheet
Table of contents
Color
I wanted to display colors in my terminal. I found this AskUbuntu article. What I liked best was this one-liner:
$ for x in {0..8}; do for i in {30..37}; do for a in {40..47}; do echo -ne "\e[$x;$i;$a""m\\\e[$x;$i;$a""m\e[0;37;40m "; done; echo; done; done; echo ""
And then this python script:
#!/usr/bin/env python
import sys
terse = "-t" in sys.argv[1:] or "--terse" in sys.argv[1:]
write = sys.stdout.write
for i in range(2 if terse else 10):
for j in range(30, 38):
for k in range(40, 48):
if terse:
write("\33[%d;%d;%dm%d;%d;%d\33[m " % (i, j, k, i, j, k))
else:
write("%d;%d;%d: \33[%d;%d;%dm Hello, World! \33[m \n" %
(i, j, k, i, j, k,))
write("\n")
Dictionary
$ sudo apt install dict
$ sudo apt install dict-gcide
I like to put this script in my ~/.bin so i can just use define word:
#!/bin/bash
ARG1=${1}
dict -d gcide $ARG1 | less
du
To show size of only top level directories in the current folder:
$ du -h -d 1
LogWatch
To setup:
$ sudo apt install logwatch
Then, edit the config at /usr/share/logwatch/default.conf/logwatch.conf, and change MailTo = user and Detail = High
Mount USB
$ sudo fdisk -l
$ sudo mount -t vfat /dev/sdb1 ~/mount -o uid=1000
When Finished:
$ sudo umount /dev/sdb1
Newsboat
To mark a single post unread, use N
To use mpv to watch videos, add this to .newsboat/config:
macro a set browser "mpv %u" ; open-in-browser ; set browser "firefox --new-tab %u"
Then to use it, go to the video post, and hit ,a. Comma is the modifer to use a macro, which we set in the config to be a.
Rsync
$ rsync -azvP -e 'ssh -p 1234' [email protected]:source dest
From the man page of rysnc:
--archive, -a archive mode is -rlptgoD (no -A,-X,-U,-N,-H)
--recursive, -r recurse into directories
--links, -l copy symlinks as symlinks
--perms, -p preserve permissions
--times, -t preserve modification times
--group, -g preserve group
--owner, -o preserve owner (super-user only)
-D same as --devices --specials
--devices preserve device files (super-user only)
--specials preserve special files
--compress, -z compress file data during the transfer
--verbose, -v increase verbosity
-P same as --partial --progress
--partial keep partially transferred files
--progress show progress during transfer
About trailing slash from stackoverflow:
A trailing slash on the source changes this behavior to avoid creating an additional directory level at the destination. You can think of a trailing / on a source as meaning “copy the contents of this directory” as opposed to “copy the directory by name”, but in both cases the attributes of the containing directory are transferred to the containing directory on the destination. In other words, each of the following commands copies the files in the same way, including their setting of the attributes of /dest/foo:
rsync -av /src/foo /dest
rsync -av /src/foo/ /dest/foo
As to the destination, I don’t think it has any major consequences. There is a difference if the source is a file and destination doesn’t exist — this will make a copy of SRC called DEST:
rsync SRC DEST
Whereas, this will create directory DEST and copy the SRC file into it:
rsync SRC DEST/
SCP
$ scp -P port [email protected]:/path/to/source /dest/
Screen
To scroll in screen, hit CTRL-a and then Esc, then you can use up and down arrows or pageup pagedown to scroll. When you’re finished, hit Esc again.
Nested Sessions
If you are using screen on your desktop, and log into a server with screen running, to send commands to the nested screen session (the server) you need to use Ctrl-a a.
So to change the active session on the server it would be Ctrl-a a n.
Know if you are in screen
To know if you are within a screen session:
$ echo $STY
If you aren’t in screen, the output will be empty. If you are it will look something like 7600.pts-1.servone.
Ssh
To close a frozen ssh session: enter ~ .
Ssh-Keygen
As of OpenSSH 9.5 ed25519 has become the default key for ssh-keygen. From what I have read this seems to be a better standard than ecdsa. So, you can now just use simply ssh-keygen with no arguments, as long as your on version 9.5 or newer. If you see it says Generating public/private rsa key pair., then you are on an older version, and will need to run it with a flag to tell it to use ed25519.
$ ssh-keygen -t ed25519
If you still want to use ecdsa:
According to ssh.com, ecdsa is:
“A new Digital Signature Algorithm standarized by the US government, using elliptic curves. This is probably a good algorithm for current applications. Only three key sizes are supported: 256, 384, and 521 (sic!) bits. We would recommend always using it with 521 bits, since the keys are still small and probably more secure than the smaller keys (even though they should be safe as well). Most SSH clients now support this algorithm.”
Create an ecdsa key with a size of 521 bits.
$ ssh-keygen -t ecdsa -b 521
Ufw
Show status
$ sudo ufw status
Show status with numbers
$ sudo ufw status numbered
Delete rule (get number with status numbered)
$ sudo delete 1
Allow port
$ sudo ufw allow 9000
Only allow from a specific IP(or range)
$ sudo ufw allow from 192.168.1.0/24 to any port 9000
Weechat (IRC)
To start mine:
$ weechat
/connect libera
I have it setup to autochange nickname and autojoin a few channels.
/set irc.server.[SERVER_NAME].nicks "nick,nick1,nick2"
/set irc server.[SERVER_NAME].autojoin "#channel1,#channel2,#channel3"
Remove sidebars:
/set buflist.look.enabled off
/set buflist.look.enabled on
/bar hide nicklist
/bar show nicklist
Wifi dongle
This worked for my DLink DWA-182
These steps from @Joe_Linux worked like a champ for Ubuntu 22.04 with EDUP wifi dongle using RTL8812au chipset.
Had to unplug then re-plug in dongle after final dkms command. Did not have to reboot.
Summary steps pulled from quoted post:
$ sudo apt install git build-essential libelf-dev linux-headers-`uname -r` debhelper dpkg-dev dkms bc
$ git clone https://github.com/aircrack-ng/rtl8812au
$ cd rtl8812au
$ sudo make dkms_install
unplug usb wifi dongle then re-plug back in.
boom. led lights up right away looking for SSIDs
thank you.