Command Line

Scanning network for ip addresees

This does a simple ping scan in the entire subnet to see which hosts │ are online.

Install nmap

sudo apt-get install nmap

nmap -sP 192.168.1.*

or more commonly

nmap -sn 192.168.1.0/24

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Cleaning and clearing logfiles

journal

Clearing out logs older than 10 days

journalctl --vacuum-time=10d

Clearing out journal more than 2 gigs

journalctl --vacuum-size=2G

Any log files

Get sizes

du -h /var/log/

Clear logs that are huge

cat /dev/null > whatever_log.log 

Setting up webservers

See web_servers.md

diff files in vim

nvim -d file1.txt file2.txt`

diff online files in vim

nvim -d <(curl -sL "https://crap.com/file1.txt") \
<(curl -sL "https://crap.com/file2.txt")

curl

See curl.md

Showing Key Codes

xev -event keyboard

Find text in a file

find . -type f -exec grep "example" '{}' \; -print

f = file

Encrypt and Decrypt

Encrypt: EASIEST OPTION

gpg -c file.txt

Alternative method:

openssl enc -aes-256-cbc -salt -pbkdf2 -in file .txt -out file.enc

Decrypt:

gpg -d file.gpg

Alternative Method: add -d to the above command

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Adding to $PATH

Simply add /place/with/the/file to the $PATH variable with the following command:

export PATH=$PATH:/place/with/the/file

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Finding directories over/under a certain size

du -sm * | awk '$1 > 1000'

This shows directories larger than 1 gig

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Star Wars Asciimation

telnet towel.blinkenlights.n

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Umcompress & Compress

7zip

Unzip zip file

7z.exe e *.zip

List files in archive

7z.exe l -r filename.zip

For tar.gz

To unpack a tar.gz file, you can use the tar command from the shell. Here's an example:

tar -xzf rebol.tar.gz

The result will be a new directory containing the files.

For just .gz (.gzip)

In some cases the file is just a gzip format, not tar. Then you can use:

gunzip rebol.gz

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Command Line Notes

September 3,2019

Courses Dashboard | Wes Bos

zsh CTRL + R lets you search through recent commands

History Example git and ⇧ goes through all git command history