I have a problem with joining two files together.

File 1
123321 abc abc
124123 abc abc
125124 abc abc
120124 abc abc
127111 abc abc
128222 abc abc

File 2
123321 10
124123 20
125124 30
128222 40


The merged file Im trying to get should look as follows;

123321 abc abc 10
124123 abc abc 20
125124 abc abc 30
128222 abc abc 40
127111 abc abc
120124 abc abc

Any suggestion how I can do that using the "join" command?

You can do:
join -a 1 -1 1 file1 -2 1 file2 |sort -k4

This will give you:
120124 abc abc
127111 abc abc
123321 abc abc 10
124123 abc abc 20
125124 abc abc 30
128222 abc abc 40

You can't make the ones without numbers appear at the bottom except by doing a reverse sort but if you do that then the numbers will be reverse as well (40, 30...).

The above doesnt seem to be doing anything all i get is.

$ join -a 1 -1 1 file1 -2 1 file2 | sort -k4
usage: join [-a file_number | -v file_number] [-o list [-e string]]
[-t char] [-1 field] [-2 field] file1 file2

join [-a file_number] [-j field] [-j1 field] [-j2 field]
[-o list [-e string]] [-t char] file1 file2

Cheers

Odd.

I tested it on Debian Woody before posting. After your response I tested it also on RH EL AS 3 and it worked as typed.

The man page and the usage you got both say -a should be followed with the file but the message I got before hitting on above was complaining about invalid index given to -a so I'd changed that.

The usage message you get seems to suggest both file names should follow the rest of the line instead of the way it worked for me.

Try doing:
join -a 1 -1 1 -2 1 file1 file2 | sort -k4

If that doesn't work retry it using "-1" or "-2" instead "1" directly after the -a.

What distro are you running?