ln -sf
does not overwrite a given symlink to a directory.
See e.g.
% ls -ld program*
drwxr-xr-x 22 b users 4096 Nov 25 14:33 program
drwxr-xr-x 22 b users 4096 Nov 25 14:29 program-201611181546
-rw-r--r-- 1 b users 0 Nov 25 14:34 program-current
% ln -fs program-201611181546 program-current
% ls -ld program*
drwxr-xr-x 22 b users 4096 Nov 25 14:33 program
drwxr-xr-x 22 b users 4096 Nov 25 14:29 program-201611181546
lrwxrwxrwx 1 b users 18 Nov 25 14:34 program-current -> program-201611181546
% ln -fs program program-current
% ls -ld program*
drwxr-xr-x 22 b users 4096 Nov 25 14:33 program
drwxr-xr-x 22 b users 4096 Nov 25 14:34 program-201611181546
lrwxrwxrwx 1 b users 18 Nov 25 14:34 program-current -> program-201611181546
I would have expected
lrwxrwxrwx 1 b users 18 Nov 25 14:34 program-current -> program
As workaround I can explicitly unlink.
% unlink program-current
% ls -ld program*
drwxr-xr-x 22 b users 4096 Nov 25 14:33 program
drwxr-xr-x 22 b users 4096 Nov 25 14:34 program-201611181546
% ln -fs program program-current
% ls -ld program*
drwxr-xr-x 22 b users 4096 Nov 25 14:33 program
drwxr-xr-x 22 b users 4096 Nov 25 14:34 program-201611181546
lrwxrwxrwx 1 b users 5 Nov 25 14:35 program-current -> program
But I would prefer ln
doing the job.
Is this possible? How?
man ln
SYNOPSIS ln [OPTION]... [-T] TARGET LINK_NAME (1st form) ln [OPTION]... TARGET (2nd form) ln [OPTION]... TARGET... DIRECTORY (3rd form) ln [OPTION]... -t DIRECTORY TARGET... (4th form) DESCRIPTION In the 1st form, create a link to TARGET with the name LINK_NAME. In the 2nd form, create a link to TARGET in the current directory. In the 3rd and 4th forms, create links to each TARGET in DIRECTORY.
You have the 3rd form, because your link is a link to a directory.