bash if equal

Use == operator with bash if statement to check if two strings are equal. You can also use != to check if two string are not equal. You must use single space before and after the == and !=

1. What is == in bash?
2. How do you check if two variables are equal in bash?
3. What is $0 $1 in shell script?
4. How do I compare two numbers in bash?
5. What is option in bash?
6. What is an array in bash?
7. How do you set a variable in bash?
8. How do you increment in bash?
9. How do you do if in bash?
10. What does echo $1 mean?
11. What do the symbol pairs of $# $? $1 $2 and $@ mean in a bash script?
12. What does echo $0 Do?

What is == in bash?

It's the other way around: = and == are for string comparisons, -eq is for numeric ones. -eq is in the same family as -lt , -le , -gt , -ge , and -ne , if that helps you remember which is which. == is a bash-ism, by the way. ... In bash the two are equivalent, and in plain sh = is the only one guaranteed to work.

How do you check if two variables are equal in bash?

Comparison Operators

When comparing strings in Bash you can use the following operators: string1 = string2 and string1 == string2 - The equality operator returns true if the operands are equal. Use the = operator with the test [ command. Use the == operator with the [[ command for pattern matching.

What is $0 $1 in shell script?

$1 is the first command-line argument passed to the shell script. Also, know as Positional parameters. ... $0 is the name of the script itself (script.sh) $1 is the first argument (filename1) $2 is the second argument (dir1)

How do I compare two numbers in bash?

Compare Numbers in Linux Shell Script

1. num1 -eq num2 check if 1st number is equal to 2nd number.
2. num1 -ge num2 checks if 1st number is greater than or equal to 2nd number.
3. num1 -gt num2 checks if 1st number is greater than 2nd number.
4. num1 -le num2 checks if 1st number is less than or equal to 2nd number.

What is option in bash?

Options are settings that change shell and/or script behavior. The set command enables options within a script. At the point in the script where you want the options to take effect, use set -o option-name or, in short form, set -option-abbrev. ... #!/bin/bash set -o verbose # Echoes all commands before executing.

What is an array in bash?

An array is a variable containing multiple values may be of same type or of different type. There is no maximum limit to the size of an array, nor any requirement that member variables be indexed or assigned contiguously. Array index starts with zero. In this article, let us review 15 various array operations in bash.

How do you set a variable in bash?

To create a variable, you just provide a name and value for it. Your variable names should be descriptive and remind you of the value they hold. A variable name cannot start with a number, nor can it contain spaces. It can, however, start with an underscore.

How do you increment in bash?

Using + and - Operators

The most simple way to increment/decrement a variable is by using the + and - operators. This method allows you increment/decrement the variable by any value you want.

How do you do if in bash?

A Shell script usually needs to test if a command succeeds or a condition is met. In Bash, this test can be done with a Bash if statement.
...
What are the Bash Conditional Expressions?

What does echo $1 mean?

$1 is the argument passed for shell script. then. $1 will be hello. $2 will be 123.

What do the symbol pairs of $# $? $1 $2 and $@ mean in a bash script?

$# Stores the number of command-line arguments that were passed to the shell program. ... "$@" Stores all the arguments that were entered on the command line, individually quoted ("$1" "$2" ...). So basically, $# is a number of arguments given when your script was executed. $* is a string containing all arguments.

What does echo $0 Do?

As explained in this comment on that answer you link to, echo $0 simply shows you the name of the currently running process: $0 is the name of the running process. If you use it inside of a shell then it will return the name of the shell. If you use it inside of a script, it will be the name of the script.