The `pgrep -x` command will report an error message when performing a length check.

if `-x `is used the length check is off by two characters (due to added ^$) - ie.  `cargo run pgrep -x 12345678901234`  will trigger the message.

```shell
$ cargo run -q pgrep -x 12345678901234
pgrep: pattern that searches for process name longer than 15 characters will result in zero matches
Try `pgrep -f' option to match against the complete command line.
```