Question: I want to get a numbered list of files, e.g. if I have these files:

```
a.pdf
b.pdf
c

```

then it should be listed as:

```
1 a.pdf
2 b.pdf
3 c

```

Answer: 
If you want to [avoid parsing the output of `ls`](http://mywiki.wooledge.org/ParsingLs) (which you do), you can do something like this:

```
$ counter=1; for f in *; do printf "%2d %s\n" $((counter++)) "$f"; done
 1 a.pdf
 2 b.pdf
 3 c

```

I only mention this because it's the path for doing more sophisticated things, not just enumerating.
Not sure why you need to use `awk` but here you go:

```
ls | awk '{print NR, $0}'

```

**updated** `$0` is better than `$1` since it will print the entire file name even with spaces (as hinted at by BroSlow)

Note - you do **not** need to use the `-1` flag with `ls` when the output is another process - it becomes the default option. Only when you want to force output to the terminal with one file per line do you need to use it.