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Bash Scripting If Else Statements

Bash scripting with if else statements

Mark Lucernas
2020-08-09

If Else Statements

Basics

if <condition>; then
  # Commands if condition is true
fi

if <condition>; then
  # Commands if condition is true
else
  # Commands if condition is false
fi

if [[ <condition> ]]; then
  # Commands if condition is true
else
  # Commands if condition is false
fi

[[ <condition> ]] && # Command is true

[[ <condition> ]] && # Command if true || # Command if false

NOTE: type man test to see some possible checks that can be used for if-else conditions.

Checks

Check if command exists or installed

  • command -v <command-to-check> – Method 1
  • hash <command-to-check> – Method 2
  • type <command-to-check> – Method 3
  • which <command-to-check> – Not recommended

Samples

command -v tmux >/dev/null 2>&1

# or

if ! command -v tmux &> /dev/null
then
  echo "Tmux could not be found"
  exit
fi

Break-like Statement for If Statements

Using : built-in shell command that does nothing.

if [[ <condition> ]]; then
  echo "Some commands"
elif [[ <condition> ]]; then
  :
else
  echo "Another commands"
fi

Ref:


Resources