regex for expression with one separator hyphen

I'm going to use regex for matching expressions, which:

1. Separated by one (and only one) hyphen
2. Each of the two parts do not contain any spaces

So, it matches:

ss-ss
12-s2
11-11
%@2s-#1

And does not match:

s s-ss
ss-s s
s s-s s
1 s-1s
1s-1 s
1 s-1 s
ss-ss-ss
s1-s2-s3

Is there any way to create with regex?

I tries something like:

^.[^ ]-[^ ]*

But it matches only expressions with any number of hyphens, and whatever space occurrence, for example

 ss-ss-ss
 1 s-1 s

The regex:

'^[^\ \-]+\-[^\ \-]+$'

should do what you want. Here's the test that I did:

$ cat x.tst
ss-ss
12-s2
11-11
%@2s-#1
s s-ss
ss-s s
s s-s s
1 s-1s
1s-1 s
1 s-1 s
ss-ss-ss
s1-s2-s3

$ egrep  '^[^\ \-]+\-[^\ \-]+$' x.tst
ss-ss
12-s2
11-11
%@2s-#1

$ egrep  -v '^[^\ \-]+\-[^\ \-]+$' x.tst
s s-ss
ss-s s
s s-s s
1 s-1s
1s-1 s
1 s-1 s
ss-ss-ss
s1-s2-s3

An Explanation:

The problem is to recognize two non-empty strings separated by a hyphen. Those two strings can't have spaces or hyphens.

• [xy]+ means "a string of 1 or more x's or y's"
• [^xy]+ means "a string of 1 or more characters with no x's or y's
• \ means "take the next character literally"
• So, [^\ \-]+ means a non-empty string with no spaces or hyphens

We want that regex twice, separated by a hyphen.

^ at the front and $ at the end mean that the match has to extend for the entire string.

Without the ^ and $, "1 s-1 s" would be a match because the "s-1" in the middle would match the regex.