Shell basic operators -- relational operators

Relational operator

Relational operators only support numbers , String not supported , Unless the value of the string is a number . The following table lists the common relational operators , Assumed variable a by 10, Variable b by 20

Operator	explain	give an example
-eq	Check whether two numbers are equal , Equal return true.	[ $a -eq $b ] return false.
-ne	Check if two numbers are not equal , Unequal return true.	[ $a -ne $b ] return true.
-gt	Check whether the number on the left is greater than that on the right , If it is , Then return to true.	[ $a -gt $b ] return false.
-lt	Check if the number on the left is less than the number on the right , If it is , Then return to true.	[ $a -lt $b ] return true.
-ge	Check whether the number on the left is equal to or greater than the number on the right , If it is , Then return to true.	[ $a -ge $b ] return false.
-le	Check whether the number on the left is less than or equal to the number on the right , If it is , Then return to true.	[ $a -le $b ] return true.

Examples of relational operators are as follows ：

1. #!/bin/bash
2. a=10
3. b=20
4. if[ $a -eq $b ]
5. then
6. echo "$a -eq $b : a be equal to b"
7. else
8. echo "$a -eq $b: a It's not equal to b"
9. fi
10. if[ $a -ne $b ]
11. then
12. echo "$a -ne $b: a It's not equal to b"
13. else
14. echo "$a -ne $b : a be equal to b"
15. fi
16. if[ $a -gt $b ]
17. then
18. echo "$a -gt $b: a Greater than b"
19. else
20. echo "$a -gt $b: a No more than b"
21. fi
22. if[ $a -lt $b ]
23. then
24. echo "$a -lt $b: a Less than b"
25. else
26. echo "$a -lt $b: a Not less than b"
27. fi
28. if[ $a -ge $b ]
29. then
30. echo "$a -ge $b: a Greater than or equal to b"
31. else
32. echo "$a -ge $b: a Less than b"
33. fi
34. if[ $a -le $b ]
35. then
36. echo "$a -le $b: a Less than or equal to b"
37. else
38. echo "$a -le $b: a Greater than b"
39. fi

Execute the script , The output is as follows ：

1. 10-eq 20: a It's not equal to b
2. 10-ne 20: a It's not equal to b
3. 10-gt 20: a No more than b
4. 10-lt 20: a Less than b
5. 10-ge 20: a Less than b
6. 10-le 20: a Less than or equal to b