Bash commands-comparison Operators

A binary comparison operator compares two variables or quantities.
Note that integer and string comparison
Use a different set of operators.

1. Integer comparison
-EQIs equal

If ["$ A"-EQ "$ B"]

-NeIs not equal

If ["$ A"-ne "$ B"]

-GTIs greater

If ["$ A"-GT "$ B"]

-GeIs greater than or equal

If ["$ A"-ge "$ B"]

-LtIs less

If ["$ A"-lt "$ B"]

-LeIs less than or equal

If ["$ A"-Le "$ B"]

<Is less than (within double parentheses)

("$ A" <"$ B "))

<=Is less than or equal to (within double parentheses)

("$ A" <= "$ B "))

>Is greater than (within double parentheses)

("$ A"> "$ B "))

> =Is greater than or equal to (within double parentheses)

("$ A"> = "$ B "))

2. String comparison

=Is equal
If ["$ A" = "$ B"]
Note the whitespace framing the =.

If ["$ A" = "$ B"] is not equivalent to the above.

=Is equal
If ["$ A" = "$ B"]
This is a synonym for =.
The = comparison operator behaves differently within a double-brackets test
Within single brackets.
[[$ A = z *]
# True if $ A starts with an "Z" (pattern matching ).
[[$ A = "z *"] # True if $ A is equal to z * (literal matching ).
[$ A = z *]
# File globbing and word splitting take place.
["$ A" = "z *"] # True if $ A is equal to z * (literal matching ).

! =Is not equal

If ["$ "! = "$ B"]

This operator uses pattern matching within a [[...] construct.

<Is less than, in ASCII alphabetical order
If [["$ A" <"$ B"]
If ["$ A" \ <"$ B"]

Note that the "<" needs to be escaped within a [] construct.

>Is greater than, in ASCII alphabetical order
If [["$ A"> "$ B"]
If ["$ A" \> "$ B"]
Note that the ">" needs to be escaped within a [] construct.

-ZString is null, that is, has zero length
String =''
# Zero-length ("null") string variable.
If [-z "$ string"]
Then
Echo "\ $ string is null ."
Else
Echo "\ $ string is not null ."
Fi

# $ String is null.

-NString is not null.

The-n test requires that the string be quoted within the test brackets. Using
Unquoted string! -Z, or even just the unquoted string alone within test brackets
Normally works, however, this is an unsafe practice. always quote
Tested string. [37]