In this section a list of all the conditional tests already discussed in the previous sections is shown and completed. The conditions are always written inside square brackets.
File operators
A series of operators exists in order to verify files conditions, according to the following syntax:
[ check_operator /etc/file_to_check]
These controls are:
| Operator | Meaning |
| -d: | Checks that the file is a directory |
| -e: | Checks that the file exists |
| -f: | Checks that the file is regular |
| -g: | Checks that the SGID bit is set |
| -r: | Checks that the file has the permissions for
reading for the user executing the script |
| -s: | Checks that the file has a non zero dimension |
| -u: | Checks that the SUID bit is set |
| -w: | Checks that the file is writable |
Number operators
Two numbers can be compared with the following tests. The variables must be written in the form:
"$variable_name"
The numerical tests are:
| Control | Meaning |
| x -eq y | true if x is equal to y |
| x -ne y | true if x is not equal to y |
| x -gt y | true if x is bigger than y |
| x -lt y | true if x is smaller than y |
| x -ge y | true if x is bigger than or equal to y |
| x -le y | true if x is smaller than or equal to y |
Strings controls
Two strings can be compared with the following tests:
"$variable_name"
These are the available scripts:
| Control | Meaning |
| x = y | true if x is equal to y |
| x != y | true if x is equal to y |
| -n x | true if x is not NULL or void |
| -z x | true if x is NULL or void |
Logical operators
The AND and OR logical operators can be used, according to the following syntax:
[ condition1 ] && [ condition2 ]
The logical operators are;
| Symbol | Meaning |
| & & | AND |
| || | OR |
