corresponding (allcaps) variable (e·g, set `MKDIR` to supply your own
`mkdir` implementation).
+- `awk`
- `cat`
- `cp`
- `date`
- `find`
- `mkdir` (requires support for `-p`)
- `mv`
+- `od` (requires support for `-t x1`)
- `printf`
- `rm`
- `sed`
- `touch`
- `tr` (requires support for `-d`)
- `uuencode` (requires support for `-m` and `-r`)
+- `xargs` (requires support for `-0`)
- `xmlcatalog` (provided by `libxml2`)
- `xmllint` (provided by `libxml2`)
- `xsltproc` (provided by `libxslt`)