Linux Test Statement (tests)

Linux Test Statements

Testing with the test command, returning 0 means that the test was successful and returning 1 indicates a failure.

1. File Status Test

File status test refers to the permissions of the file, there is no, attributes, types and other content to judge.

File Test parameter list

-d test file is a catalog file	-S test file is not empty
-F Test file is a regular file	-W test file is writable
-L Test if the file is a symbolic connection	-U Test whether the file has suid bit settings
-X Test whether the file can be executed	-R Test file is readable

2. Numerical test

The numerical test is to compare the size relationship of two values

1) test grammar with the test command: Test first operand numeric comparer second operand

2) use [] instead of the test command syntax:[ first operand numeric comparer second operand ]

Note:[ must have a space ] before must also have a space

Numeric comparison characters

-eq equals	-ne Not equal to
-ge greater than or equal to	-GT greater than
-le less than or equal to	-lt less than

3. String test

A string test is to compare two strings for equality, or to determine whether a string is empty

The method is similar to a numeric test by comparing the following characters:

= tests whether two strings are equal	! = Tests whether two strings are not equal
-Z Test string is empty	-N test string is non-null

4. Logic Test

-A: logical and, when both sides of the operator are true, the result is true, otherwise the result is false.

-O: logical OR, at least one of the operators is true, the result is true, otherwise false.

！ : Logical No, only if the condition is false - Returns the result as true

Linux Test Statement (tests)