Terminal tips and tricks

contents:

My favourites
Basics
Advanced
Editors
Environment
Win / Mac / GNU workarounds
Shortcuts

1) My favourites

List the lines from a text (here: history) which contains a keyword (here: git):

history | grep git
history | awk '/git/ {print}'

Last 15 only:

history | grep git | head -n 15

get the folders updated since a given date:

find . -maxdepth 1 -type d -newermt "2023-05-24 00:00:00" |
awk -F/ '{print $NF}'

Show hidden files in Mac's file manager (Finder): Open Terminal and run the following script:
defaults write com.apple.Finder AppleShowAllFiles true
killall Finder
Count how many times a word appears in a file:

  cat PATH/TO/FILE/index.js | grep somefunkyword | wc -l

You will want to use awesome additional commands like tree. You have too install Homebrew, so adding these extras will be super simple.

2) Basics

go to a folder cd folderName
leave the folder, go to its parent folder cd ..
go to the root folder cd ~
go to the home folder cd $HOME
create a new folder mkdir folderName
if you have an opened file or process in terminal and would like t o exit, you should try Control C or q

Main commands and operators

command	description
`pwd`	see in terminal the current your current path (which folder you are in)
`man pwd`	documentation of the command
`cd, ls, ls -l, ls -a`	moving in folder structure (c hange d irectory), list folder content
`mkdir`, `touch`	create folders and files
`cat a.txt`, `less b.txt`, `more c.txt`, `awk '{print}' d.txt`	read file to standard output (practically: print to console). `less` and `more` create a scrollable print
`env`, `printenv`	list environmental variables
`date`	print date
`history`	terminal command history (terminal-window related so don't trust it too much)
`ifconfig`	list computer ip, environmental variables
`grep`	search text. It can be used in terminal like `grep text in filename` see examples here but it is also very common to pipe an output to it. For example: `history \| grep code` extracts all the commands from terminal history where we opened a file with VS Code
pipe `\|`	read the output of a function and pass it to another function see example here
`tail -99 c.txt`	read last 99 lines of a file to standard output
`wc index.html`	count characters, words and lines in a specific file
`ls \| wc -w`	count files/folders in a folder

More complicated commands with a typical example

command	example	description
`sed`	`sed -i 's/80/5000/g' target/tobeedited.txt`	find and replace text `80` to `5000` in a file
`awk`	`ls -la \| awk '{print $3, $9}'`	show words from lines by their word count index

more about awk

folder name and date in this format: 536daysoftype - May 7

  ls -la | awk '{print NR $9 " - " $6 " "  $7 }'

longest line and its length

  ls -la | awk '{ if (length($0) > max) max = length($0) } END {print "length: " max "         - " $0}'

NR: Represents the current record number (line number) being processed.
NF: Represents the number of fields (columns) in the current record.
$0: Refers to the entire input record (the full line).
$1, $2, $3, etc.: Represent the individual fields (columns) of the input record. $1 refers to the first field, $2 to the second field, and so on.
FS: Specifies the input field separator (default is whitespace).
RS: Specifies the input record separator (default is newline).
OFS: Specifies the output field separator (used when printing fields).
ORS: Specifies the output record separator (used when printing records).
FILENAME: Contains the name of the current input file being processed.
FNR: Represents the record number (line number) within the current input file.
ARGC: Contains the total number of command-line arguments.
ARGV: An array that stores the command-line arguments passed to awk.

3) Advanced

find your running server and stop it You can do it by listing the running processes on your computer. If you have a running server (like Node.js or Tomcat) on a port (like 8080, 3000 etc.), you will see in the list that your server is there, like 0.0.0.0:8080. Copy the identifier of that process and stop it like below!

GNU/Linux and Mac
sudo lsof -i -P -n | grep LISTEN
kill 27746
ping an API with curl : instead of opening a URL in the browser, or using Postman, you can do this in the terminal.
curl https://github.com
curl -i -X POST -H "Content-Type: multipart/mixed" -F "uploadParams={\"one_parameter\":\"one_value\"};type=application/json" -F "file=@/Users/user/Downloads/gangstercar.jpg" http://localhost:7000/myapplication/services/myendpoint

4) Editors

You may use VS Code or Jetbrains for your code, but there are also command line editors. Vim and Emacs are old, powerful ones but it is not so easy to work with them. nano is more handy. Of course you can also avoid the usage of command line editors.

❗ important: Git may open the editor in some situations. The default file editor of Git is Vim. If you are not comfortable with Vim, change your default code editor in Git settings to nano or VS code:
git config --global core.editor "nano"
git config --global core.editor "code"

5) Bash shell scripts

Shell scripts, like bash are (usually) simple scripts, which you can run in your terminal. It is the "language of the terminal", so you don't have to install anything. Here is an example you can save as fruits.sh and try:

#! /bin/bash

WELCOME="Welcome to bash!"
echo $WELCOME

for x in $@
  do
    echo "I got a parameter: $x"
    if [[ $x == "strawberry" ]]
    then
      echo "it is a fruit"
    else
      echo "need some cream on the top?"
    fi
  done

Run bash script:

  bash ./fruits.sh strawberry chocolate

Most common shells on Linux / Mac

sh or Bourne shell
bash or Bourne Again Shell
zsh or z-shell (originates from the name of professor Zhong Shao)

note: for shell script files you can use always .sh extension (it is not required, just convention)

6) Environment

For handling environmental variables in Windows command line (CMD), check out this StackOverflow article.

Create environmental variables

You can create an environmental variable on Linux / Mac with
export PORT=8080
If you don't need it any more, remove it with
unset PORT.

You can use bash to define environmental variables and script you use often in an envsetter.sh

#!/bin/sh

#Remote
#echo - Setting variables  

export HOPHOPHOP_DB_PW="gangnam-style"
export HOPHOPHOP_DB_HOST="jdbc:postgresql://localhost:2345/postgres?"

alias runjacoco='mvn clean org.jacoco:jacoco-maven-plugin:prepare-agent install'
alias runsonar='mvn sonar:sonar'

unset HOPHOPHOP_DB_HOST

The main place to set environmental variables and Path is the .bash_profile in the root folder: ~/.bash_profile

PATH=${PATH}:~/bin
PATH=${PATH}:/usr/local/bin

export MYVARIABLE=soma/text/for/you

Starting your Mac will run .bash_profile. If you would like to run it without restart, you should run it:

source ~/.bash_profile

Certificates

install certificate files
sudo keytool -import -alias CERTIFICATE_NAME -file "CERTIFICATE_FILENAME.cer" -keystore cacerts -storepass changeit

7) Tools to be installed

Homebrew and wget

It is a just a must to have the number one package manager and wget for recursive resource downloads. Follow Homebew website to install brew and wget:

/usr/bin/ruby -e "$(curl -fsSL https://raw.githubusercontent.com/Homebrew/install/master/install)"
$ brew install wget

Homebrew services is also essential to maintain services on you Mac. You can install, start, stop, view background services like redis or mysql:

brew services start redis
brew services restart redis
brew services stop redis
brew services list

Tree View folder structure in terminal is just a must: brew install tree

7) Shortcuts

terminal clear: Command + K

somahargitai/TerminalCheatSheet.md