Do trailing slashes or leading dot-slashes ever matter?

[davejjj]

ls mydir
ls ./mydir
ls mydir/
ls ./mydir/
cp xxx mydir
cp xxx ./mydir/


???

[sgosnell]

AFAIK the only time you need the ./ is when you want to run an executable file in the current directory. ./ tells bash to look in the current directory for a command instead of looking in the path. If you want to copy to the current directory, just use the period, not the slash, as in

cp xxx .

Using ls you don't need anything, because the default, with no other modifiers, is to list the contents of the current directory.

[Cabhan]

They can affect things.

sgosnell discusses the "./" prefix: it can sometimes change a bareword into a relative path, and this is used, for example:

ls # Run the standard "ls" command (probably /bin/ls)
./ls # Run a program called "ls" in the current directory
bin/ls # Run a program caled "ls" in the bin/ directory
./bin/ls # Same as above

For the case of a trailing slash, this can sometimes matter. A pretty standard example of this is for symlinks to directories:

[alex@niamh ~]$ ls -l test_symlink # List the symlink itself
lrwxrwxrwx 1 alex users 4 Oct 23 23:45 test_symlink -> test
[alex@niamh ~]$ ls -l test_symlink/ # List the contents of the link target dir
total 12
drwxr-xr-x 2 alex users 4096 Oct 22 10:45 c
drwxr-xr-x 2 alex users 4096 Oct 22 10:45 perl
drwxr-xr-x 2 alex users 4096 Oct 22 10:45 ruby