Common comparison operators in shell programming

Conditional judgment statements are not necessary in any program writing, as is the case in shell programming, where the comparison operators that are often used in the shell's test commands are sorted into numeric comparisons, string comparisons, and file comparisons.

Numerical comparison:

N1-eq N2	Check if N1 is waiting for N2
N1-ge N2	Check if N1 is greater than or equal to N2
N1-GT N2	Check if N1 is greater than N2
N1-le N2	Check if N1 is less than or equal to N2
N1-lt N2	Check if N1 is less than N2
N1-ne N2	Check if N1 is not equal to N2

string comparison:

STR1 = str2	Check if STR1 is the same as str2
Str1! = str2	Check if STR1 is different from str2
STR1 < STR2	Check if STR1 is smaller than str2
str1 > STR2	Check if STR1 is bigger than str2.
-N str1	Check that the length of the str1 is not 0
-Z str1	Check if the length of the str1 is 0

File comparison:

-D File	Check if file exists and is a directory
-E File	Check if file exists
-F File	Checks if file exists and is a file
-R File	Check if file exists and is readable
-S file	Checks if file exists and is not empty
-W File	Checks if file exists and is writable
-X File	Check if file exists and can be executed
-O File	Checks if file exists and is owned by the current user
-G file	Checks if file exists and the default group is the same as the current user
File1-nt File2	Check if File1 is newer than file2
File1-ot File2	Check if File1 is older than file2

Common comparison operators in shell programming