A large number of unix utilities have two letter names, like rm, mv, cp etc. You may have wandered which have already been used. There is a very high chance that all 676 possible ones have been used by someone, but here is a list of the ones found in the Arch repos.
Generated on 2024-01-10. 139 valid two letter commands were found. Code for generating this document is included as a comment at the end.
ab:- extra/apache
ag:- extra/the_silver_searcher
al:- extra/mono
ar:- core/binutils
- extra/aarch64-linux-gnu-binutils
- extra/arm-none-eabi-binutils
- extra/lm32-elf-binutils
- extra/mingw-w64-binutils
- extra/mingw-w64-binutils
- extra/nds32le-elf-binutils
- extra/or1k-elf-binutils
- extra/ppc64le-elf-binutils
- extra/riscv32-elf-binutils
- extra/riscv64-elf-binutils
- extra/riscv64-linux-gnu-binutils
- extra/sh2-elf-binutils
- extra/sh4-elf-binutils
as:- core/binutils
- extra/aarch64-linux-gnu-binutils
- extra/arm-none-eabi-binutils
- extra/lm32-elf-binutils
- extra/mingw-w64-binutils
- extra/mingw-w64-binutils
- extra/nds32le-elf-binutils
- extra/or1k-elf-binutils
- extra/ppc64le-elf-binutils
- extra/riscv32-elf-binutils
- extra/riscv64-elf-binutils
- extra/riscv64-linux-gnu-binutils
- extra/sh2-elf-binutils
- extra/sh4-elf-binutils
at:- extra/at
bc:- extra/9base
- extra/bc
- extra/plan9port
bf:- extra/haskell-brainfuck
bw:- extra/bitwarden-cli
cb:- extra/plan9port
cc:- core/gcc
- extra/ccache
- extra/colorgcc
- extra/distcc
ci:- extra/rcs
cl:- extra/cliquer
cm:- extra/proxmark3
co:- extra/rcs
cp:- core/coreutils
cs:- extra/csound
ct:- extra/ct
cu:- extra/uucp
db:- extra/plan9port
dc:- extra/9base
- extra/bc
- extra/plan9port
dd:- core/coreutils
- extra/9base
- extra/plan9port
df:- core/coreutils
dp:- extra/festival
du:- core/coreutils
- extra/9base
- extra/plan9port
ec:- extra/editorconfig-checker
ed:- core/ed
- extra/9base
- extra/plan9port
eg:- extra/go-tools
ex:- core/vi
fb:- extra/fb-client
fd:- extra/fd
fn:- extra/findnewest
fp:- extra/fpc
fq:- extra/fq
fx:- extra/fx
gc:- extra/graphviz
gh:- extra/github-cli
gm:- extra/graphicsmagick
gn:- extra/gn
go:- core/gcc-go
- extra/go
- extra/go
gp:- extra/pari
gs:- extra/ghostscript
gv:- extra/gv
he:- extra/ansible-language-server
- extra/hedgedoc
- extra/matrix-appservice-irc
- extra/opensearch-dashboards-observability-plugin
- extra/s3rver
- extra/vscode-markdown-languageserver
- extra/vue-language-server
hg:- extra/mercurial
hq:- extra/hq
ht:- extra/texlive-plaingeneric
hx:- extra/hex
hy:- extra/hy
ia:- extra/python-internetarchive
id:- core/coreutils
ig:- extra/igrep
io:- extra/io
ip:- core/iproute2
iv:- extra/openimageio
iw:- core/iw
jc:- extra/jc
jo:- extra/jo
jq:- extra/jq
jw:- extra/docbook-utils
kn:- extra/knative-client
ko:- extra/ko
lc:- extra/mono
- extra/plan9port
ld:- core/binutils
- extra/aarch64-linux-gnu-binutils
- extra/arm-none-eabi-binutils
- extra/lm32-elf-binutils
- extra/mingw-w64-binutils
- extra/mingw-w64-binutils
- extra/nds32le-elf-binutils
- extra/or1k-elf-binutils
- extra/ppc64le-elf-binutils
- extra/riscv32-elf-binutils
- extra/riscv64-elf-binutils
- extra/riscv64-linux-gnu-binutils
- extra/sh2-elf-binutils
- extra/sh4-elf-binutils
lf:- extra/lf
li:- extra/orbiton
ln:- core/coreutils
lp:- extra/cups
ls:- core/coreutils
- extra/9base
- extra/plan9port
ly:- extra/python-ly
lz:- extra/mtools
mc:- extra/mc
- extra/plan9port
mf:- extra/texlive-bin
mg:- extra/mg
mk:- extra/9base
- extra/plan9port
mr:- extra/myrepos
mv:- core/coreutils
nc:- extra/gnu-netcat
- extra/openbsd-netcat
nl:- core/coreutils
nm:- core/binutils
- extra/aarch64-linux-gnu-binutils
- extra/arm-none-eabi-binutils
- extra/lm32-elf-binutils
- extra/mingw-w64-binutils
- extra/mingw-w64-binutils
- extra/nds32le-elf-binutils
- extra/or1k-elf-binutils
- extra/ppc64le-elf-binutils
- extra/riscv32-elf-binutils
- extra/riscv64-elf-binutils
- extra/riscv64-linux-gnu-binutils
- extra/sh2-elf-binutils
- extra/sh4-elf-binutils
nu:- extra/nushell
od:- core/coreutils
og:- extra/orbiton-gtk3
ol:- extra/owl-lisp
pc:- extra/profile-cleaner
pd:- extra/pd
- extra/pd
pg:- core/util-linux
pi:- extra/cln
pl:- extra/gnustep-base
pm:- extra/festival
pr:- core/coreutils
- extra/plan9port
ps:- core/procps-ng
- extra/plan9port
pv:- extra/pv
qr:- extra/python-qrcode
rc:- extra/9base
- extra/plan9port
rg:- extra/code
- extra/ripgrep
ri:- extra/jruby
- extra/ruby-rdoc
rm:- core/coreutils
- extra/plan9port
rp:- extra/rosenpass
rq:- extra/rq
rw:- extra/rankwidth
sc:- extra/sc
sd:- extra/sd
sg:- core/shadow
sh:- core/bash
sk:- extra/skim
sl:- extra/sl
sm:- extra/inn
- extra/proxmark3
sn:- extra/mono
sq:- extra/sequoia-sq
sr:- extra/surfraw
ss:- core/iproute2
su:- core/util-linux
sw:- extra/orbiton
sx:- extra/sx
sz:- extra/sz
tc:- core/iproute2
tk:- extra/tanka
tr:- core/coreutils
- extra/9base
- extra/plan9port
ts:- extra/moreutils
tt:- extra/ruby-treetop
- extra/ruby-treetop
ug:- extra/ugrep
ul:- core/util-linux
up:- extra/up
uz:- extra/mtools
vd:- extra/visidata
vg:- extra/orbiton-gtk3
vi:- core/vi
vs:- extra/orbiton
wc:- core/coreutils
- extra/plan9port
wg:- extra/wireguard-tools
wp:- extra/wp-cli
xa:- extra/xa
xd:- extra/plan9port
xh:- extra/xh
xq:- extra/yq
xz:- core/xz
yq:- extra/go-yq
- extra/yq
zk:- extra/zk