shell: errno memo

errno () (
    [ "$1" ] && filter="grep -i \"$1\" |"
    filter="$filter column -t"
    cmd="cc -E -dM /usr/include/errno.h |
            grep 'define E' |
            sort -n -k 3 |
            cut -d' ' -f2- |
            $filter"
    eval $cmd
)

$ errno 26
ETXTBSY  26
ENOKEY   126
$ errno ENOBUFS
ENOBUFS  105