Conditional judgment statements: files, numeric values, strings

You can test whether a condition is true with test or []. If the test result is true, the exit status of the command is 0, if false, the status is 1.

File testing

Format: test option file or [option file]

-b file block file

-c file character file

-d file directory

-e file exists

-p file pipeline

-r file readable

-s file greater than 0

-w file writable

-x file executable

F1-ef f2 F1 and f2 are linked to the same file (Korsh shell)

F1-nt f2 F1 is newer than f2

F1-ot f2 F1 is older than f2

The-a logic and the operator are true on both sides, and the result is true, otherwise it is false.

-o logical OR, either side of the operator is true, the result is true, otherwise it is false.

! Logic no, the condition is false, the result is true

Integer comparison test

Format: test int1 operator int2

-eq values are equal.

-ne values are not equal.

-the first number of gt is greater than the second number.

-the first number of lt is less than the second number.

-le the first number is less than or equal to the second number.

-ge the first number is greater than or equal to the second number.

N1-eq N2 N1 and N2 are equal

N1-ge N2 N1 is greater than or equal to N2

N1-gt N2 N1 is greater than N2

N1-le N2 N1 is less than or equal to N2

N1-lt N2 N1 is less than N2

N1-ne N2 N1 is not equal to N2

String test

Format: test option string or [option string]

= two strings are equal.

! = two strings are different.

-z empty string.

-n non-empty string.

S1 = S2 equal

S1! = S2 S1 is different from S2

S1

< s2 s1的ASCII在s2前 s2 >

ASCII of S2 S1 after S2