nestrada2 commented 2 months ago

test

The "test" command evaluates a conditional expression. It is an if statement that will return zero (true) or 1 (false), or greater than 1 (error).

Approach

The "test" command will check if any flags were inputted and, based on the expression, will return a truthy or falsy value. For example,test -e myfile.txt will return 0 if that file exists. Will have to use the sys_fstat to obtain information about the specified file.

Files to be Modified/Added

user:

user.h (add test)
test.c (new: call sys_open, pass a path to that and that will give us a file descriptor. With the file descriptor we call sys_fstat, and pass in an file descriptor, and a pointer to an empty stat struct which is an output, it is going to modify it)

Subcommands Implemented in Test

Command	Description
-d file	True if file exists and is a directory.
-e file	True if file exists (regardless of type).
-f file	True if file exists and is a regular file.
file1 -ef file2	True if file1 and file2 exist and refer to the same file.
s1 = s2	True if the strings s1 and s2 are identical.
s1 != s2	True if the strings s1 and s2 are not identical.
n1 -gt n2	True if the integer n1 is algebraically greater than the integer n2.
n1 -lt n2	True if the integer n1 is algebraically less than the integer n2.

Future Development

Add functionality for more flags Add logical operators for combining expressions Edit sh so that test can be incorporated in shell scripting

References

man test

malensek commented 2 months ago

This sounds like a good project, although I don't think there is any reason to modify kernel space. The stat system call should already be enough for getting file system information. When you get a chance, can you specify the exact test features you plan to implement?