bash.md

Bash

Compression

Create a .tar.gz or .zip file

tar -czvf file.tar.gz directory-to-compress/
zip -r file.zip directory-to-compress/

Extract contents of a .tar.gz or .zip file

tar -zxvf file.tar.gz
unzip file.zip

SSH & GPG

Create SSH key pair and connect SSH with this key

ssh-keygen -f file_name -C "Comment" # prompts for passphrase
ssh-copy-id -i file_name.pub user@host
ssh -i file_name user@host

Import public key of someone

gpg --import some-one.key

See all imported public keys

gpg --list-keys

Encrypt a file

gpg --encrypt --armor -r [email protected] file.txt # or
gpg -e -u "Sender Name" -r "Receiver Name" file.txt

Decrypt a file

gpg -d file.txt.gpg            # to show content directly in bash or
gpg -d file.txt.gpg > file.txt # to create decrypted file

Add existing private SSH key to bash

chmod 600 private.key # set permissions to be only read-writable by me
eval $(ssh-agent -s)  # start ssh agent in background
ssh-add private.key   # add SSH private key to bash

PDF

Count the words of a PDF file:

pdftotext myfile.pdf - | wc -w

Password Generation

Quickly create a random string to use for passwords:

date +%s | sha256sum | base64 | head -c 32 ; echo

Get public IP address

curl ipinfo.io/ip

MySQL

Run database import file on server (corresponding to the phpMyAdmin importer)

mysql -u database_user -p database_name < file.sql
mysql -u database_user -p -h database_host database_name < file.sql # if it's not localhost

Create database export file

mysqldump -u database_user -p database_name > file.sql

Line Endings

Convert all PHP files in the current directory to Unix line endings

find "./" -type f -name '*.php' -execdir dos2unix {} +

Python

Update all outdated packages at once

pip list --outdated --format=freeze | grep -v '^\-e' | cut -d = -f 1 | xargs -n1 pip install -U