Bash Operators

Used in Bash Scripts to compare values with each other.

String Operators

• ==: Equal to
• !=: Not equal to
• <: Less than in ASCII alphabetical order
• >: Greater than in ASCII alphabetical order
• -z: The string is empty (null)
• -n: The string is not null
• #variable: Number of characters in variable.

Integer Operators

• -eq: Equal to
• -ne: Not equal to
• -lt: Less than
• -le: Less than or equal to
• -gt: Greater than
• -ge: Greater than or equal to

Logical Operators

• !: Logical NOT
• &&: Logical AND
• ||: Logical OR

File Operators

• -e: if the file exist
• -f: tests if it is a file
• -d: tests if it is a directory
• -L: tests if it is if a symbolic link
• -N: checks if the file was modified after it was last read
• -O: if the current user owns the file
• -G: if the file’s group id matches the current user’s
• -s: tests if the file has a size greater than 0
• -r: tests if the file has read permission
• -w: tests if the file has write permission
• -x: tests if the file has execute permission

Arithmetic Operators

• +: Addition
• -: Subtraction
• *: Multiplication
• /: Division
• %: Modulus
• variable++: Increase the value of the variable by 1
• variable--: Decrease the value of the variable by 1

Function Operators

• ?: The return value of the most recently run function.