Shell if statement Parameters

◆ Parameter description
-B. returns true if the file exists and is a block file.
-C: returns true if the file exists and is a character file.
-D. If pathname exists and is a directory, true is returned.
-E: returns true if the file or directory specified by pathname exists.
-F returns true if the file exists and is a regular file
-G returns true if the file or directory specified by pathname exists and the sgid bit is set.
-H returns true if the file exists and is a symbolic link file. This option is invalid in some old systems.
-K. If a file or directory specified by pathname exists and a "Sticky" bit is set, the system returns the true value.
-P: returns true if the file exists and is a command pipeline.
-R: returns true if the file or directory specified by pathname exists and is readable.
-S: returns true if the file size is greater than 0.
-U returns true if a file or directory specified by pathname exists and SUID is set.
-W returns true if the file or directory specified by pathname exists and is executable. A directory must be executable for its content access.
-O returns true if a file or directory specified by pathname exists and the user specified by the valid user ID of the current process is owned by it.

◆ Single branch structure
Syntax:
If condition
Then command
Fi
Or
If condition; then Command
Fi
Tip: a semicolon is equivalent to a line feed. The above two syntaxes are equivalent.

◆ Dual Branch Structure
Syntax:
If condition
Then
Instruction Set
Else
Instruction Set
Fi

◆ Multi-branch structure
Syntax:
If condition
Then command
Elif Condition
Then command
Else
Command
Fi