Flow

Bash Test Conditionals

• Testing conditions is down to using square bracket syntax:

if [ 1 = 3 ] || [ 2 = 2 ]; then
echo "yes!"
fi

• To note, double brackets are a BASH-ism and not POSIX compliant. To test multiple conditions for the same evaluation do not use the internal -a for and or the -o for or like:

if [ 1 = 3 -o 2 = 2 ]; then
echo "yes!"
fi

• Instead separate the tests into separate commands with the && operator. This way it will run each test as a separate command, AND it will only continue forward if the condition is true:
• <this has to be true> && "AND" <this has to be true, to continue>.
• Double quote Bash Variables (Private) use in the test condition unless you explicitly know and understand why they should be unquoted.

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Children

1. Case
2. If Else
3. Loops
4. Ternary Test