Why does the "ls -l /bin" command show only 1 file?

Question

The ls /bin command shows many files. I need to get a detailed list. But the ls -l /bin command shows only 1 file.

Tell me, please, what is wrong?

Answer 1

Nothing is wrong.

/bin is a symlink that points to /usr/bin.

When you use the ls /bin command, the symlink is followed, and you're shown the contents of /usr/bin (where the symlink points).

However, with the ls -l /bin command, the symlink is not followed, and only the symlink itself is shown.

The reason may be found under the --dereference-command-line-symlink-to-dir option in the ls texinfo documentation (info ls or info coreutils 'ls invocation'):

‘--dereference-command-line-symlink-to-dir’
     Do not dereference symbolic links, with one exception: if a command
     line argument specifies a symbolic link that refers to a directory,
     show information for that directory rather than for the link
     itself.  This is the default behavior when no other
     dereferencing-related option has been specified (‘--classify’
     (‘-F’), ‘--directory’ (‘-d’), (‘-l’), ‘--dereference’ (‘-L’), or
     ‘--dereference-command-line’ (‘-H’)).

In this context, -l is an "other dereferencing-related option" and turns the behavior off.

If you use ls -lH /bin, you tell the command to specifically follow symlinks, and now you (properly) see the contents of /usr/bin.

/bin being a symlink to /usr/bin follows the UsrMerge package, which was introduced in Debian 10 in 2019, and thus adopted by the following versions of Ubuntu.