[Good output]
term% mount -c /srv/dos /n/9 /dev/sdC0/9fat
dossrv 404:<-Tversion tag 65535 msize 8216 version '9P2000'
dossrv 404:->Rversion tag 65535 msize 8216 version '9P2000'
dossrv 404:<-Tauth tag 2 afid 272 uname glenda aname /dev/sdC0/9fat
dossrv 404:->Rerror tag 2 ename dossrv: authentication not required
dossrv 404:<-Tattach tag 2 fid 272 afid -1 uname glenda aname /dev/sdC0/9fat
alloc "/dev/sdC0/9fat", dev=3...[tread 0+0...done]magic: 0xeb 0x58 0x90
version: "Plan9.00"
sectsize: 512
clustsize: 8
nresrv: 2
nfats: 2
rootsize: 512
volsize: 0
mediadesc: 0xf8
fatsize: 100
trksize: 63
nheads: 255
nhidden: 63
bigvolsize: 204800
driveno: 128
reserved0: 0x00
bootsig: 0x29
volid: 0x00000000
label: "PLAN9      "
fatbits=16 (25572 clusters)...fat 0: 2...fat 1: 102...root: 202...data: 234...dossrv 404:->Rattach tag 2 qid (0000000000000000 0 d)

[Bad output]
term% mount -c /srv/dos /n/9 /dev/sdC0/9fat
dossrv 404:<-Tversion tag 65535 msize 8216 version '9P2000'
dossrv 404:->Rversion tag 65535 msize 8216 version '9P2000'
dossrv 404:<-Tauth tag 2 afid 272 uname glenda aname /dev/sdC0/9fat
dossrv 404:->Rerror tag 2 ename dossrv: authentication not required
dossrv 404:<-Tattach tag 2 fid 272 afid -1 uname glenda aname /dev/sdC0/9fat
alloc "/dev/sdC0/9fat", dev=3...[tread 0+0...done]bad sig 13 00 00nfree "/dev/sdE2/9fat", dev=3...dossrv 911:->Rerror tag 7 ename unknown format
mount: mount /n/9: unknown format