```
paccache -r
xargs: Cannot open input file `/dev/fd/63': No such file or directory
```

This is caused by the `runcmd()` function using sudo which will close all file descriptors except for stdin, stdout and stderr.

# Steps to reproduce
1. paccache -r
2. Failure

# Expected results
paccache correctly passing the candidates to `rm`

# Workaround
Remove `runcmd` from lines 523 and 525 and fail if not run with appropriate privileges. This would make it more consistent with the other tools which require root, e.g. `pacman -S` returns `error: you cannot perform this operation unless you are root` instead of prompting for a password.