some basic bash

conditionals.sh

num=10

# -eq equals
# -ne not equal
# -gt greather than
# -ge greather than or equal
# -lt less than
# -le less than or equal

if [ $num -eq 10]
then
 echo "condition is true"
else 
  echo "condition is false"
fi # always close the if statement

## check the prescence of a file

# -f for file
# -d for directory

if [ -f ~/some-file ]
then
 echo "file exists"
else 
  echo "file does not exist"
fi
#!/bin/bash

# which - checks whether a binary, command is present on the file system

command=/usr/local/bin/htop # fully qualified path

if [ -f $command]
then
  echo "$command is available, running it"
else
  echo "fuck you, installing it..."
  # apt update (Debian, Ubuntu) is not what it sounds, it does not update packages, instead it synchronize with the mirror, the repository
  # to find out what packages are actually available
  
  # -y means assume yes, don't give me a confirmation prompt
  
  # sudo apt update && sudo apt install -y htop # on linux
  brew install htop # on macOS
fi

$command # run the command


## check command's existence dynamically

theCommand=htop

# note we're not using brackets, brackets are only needed when running the `test` command, even thou we didn't type out the `test` command
# when using [] in a if statement we're using the `test` command
if  command -v $theCommand 
# `command -v` checks the existence of a command 
then
  echo "$theCommand is available, running it"
else
  echo "fuck you, installing it..."
  brew install $theCommand # on macOS
fi

detect-os-type.sh

#!/bin/bash

# To detect whether a bash script is running on Linux or macOS, you can check the value of the $OSTYPE environment variable. 
# The $OSTYPE variable contains information about the operating system type. 
# On Linux, it typically has a value like "linux-gnu," and on macOS, it usually has a value like "darwin."

if [[ "$OSTYPE" == "linux-gnu"* ]]; then
    echo "Running on Linux"
elif [[ "$OSTYPE" == "darwin"* ]]; then
    echo "Running on macOS"
else
    echo "Unsupported operating system"
fi

script.sh

#!/bin/bash

# the shebang is the very first line in any script that tells the script which interpreter is suppose to use

## commands

# print to the console

echo "que pasa papi"

echo "my current directoryis: " 
pwd

variables.sh

#!/bin/bash

## variables

# to create a variable just simply write the name following the = sign with no empty space in between
name_of_var="value"

# whenever we reference a variable in bash, we have to include the $ sign in front of the name of the variable

echo $name_of_var

ls="yeah"

# if you type ls, bash knows that is a command because it doesn't have the $ in front of it

echo $ls # "yeah"


age=34

echo "I'm $age years old"

## capture the output of a command

# so you make a variable that's equal to the output of a command
files=$(ls) # we use parentesis