Based on the question: How to make using command prompt less painful, what are the . and .. entries in the most voted answer? I see it when I do a dir command but it isn't visible to the user in the form of a file.
In case you dont know what I mean here's an example:
.
..
Su.exe
Sup.txt
SuperUser.COM
The . is the current directory, while .. signifies the parent directory. It makes things quicker at the command line as well so you don't need to type out full paths.
example:
go up 2 directories:
cd ..\..\
or on a UNIX based system, to run executable binaries in the current directory:
./program
A lot of UNIX scripts will also utilize . to represent the current directory, in order to scan for files for example (Perl):
#!/usr/bin/perl
opendir ( DIR, "." ) || die "Error opening current directory\n";
while( ($f = readdir(DIR))){
print("$f\n");
}
closedir(DIR);
It is much more portable if you wish to move the script around to different directories or systems since a directory name is not hard-coded.
cd ... works for me on Windows 98's command. Windows XP doesn't seem to support it though.
The .. is used to navigate up the hierarchy of the file system. It's useful when you don't want to type a long path, or when writing a script/program that doesn't know where exactly it will be installed but it knows that ../media/ should hold all the images/videos/icons etc.
The single dot . is useful in linux where you want to run an executable in the current directory so you type ./a.out because the command shell by default doesn't search the current directory for executable files (for security reasons).
The single dot . is also used if you want to pass the current directory as an argument to a command.
ls . you are passing '.' as an argument to 'ls'; isn't that what you asked? It functions the same because by default ls lists the current directory, and . is the current directory. But you are passing it to the command, for sure.
The . is the current directory. You rarely need to use this; most commands will assume the current directory. The .. is the next level up; this is a rather useful shortcut. If you are in C:\foo\bar and you want to go to C:\foo\bar2 you can say
cd ..\bar2
and you will be in C:\foo\bar2. If you don't want to go to bar2 but only want to run C:\foo\bar.exe, then you can say
..\bar.exe
or ..\bar to run it without going back up to the parent directory. Of course, this is more useful when you are it represents a longer path that C:\foo (such as "C:\Users\Daniel\My Dropbox\".
copy F:\*.foo .) or referring to it otherwise (start . opens the Explorer in the current directory, for example).
They stand for:
.
The current dir
..
Represents the parent dir
So if you have the executable "su.exe" in:
You could execute each one like this:
su.exe
Executes the one in the Path
.\su.exe
Executes the one in the current dir
..\su.exe
Executes the one in the parent dir.
