Standard input is empty

I promise I'm not trying to hack CompileBot. I'm just curious.
/bin:
bash
bunzip2
bzcat
bzcmp
bzdiff
bzegrep
bzexe
bzfgrep
bzgrep
bzip2
bzip2recover
bzless
bzmore
cat
chgrp
chmod
chown
cp
dash
date
dd
df
dir
dmesg
dnsdomainname
domainname
echo
egrep
false
fgrep
findmnt
fuser
grep
gunzip
gzexe
gzip
hostname
ln
login
ls
lsblk
mkdir
mknod
mktemp
more
mount
mountpoint
mv
nisdomainname
pidof
pwd
rbash
readlink
rm
rmdir
run-parts
sed
sh
sh.distrib
sleep
stty
su
sync
tailf
tar
tempfile
touch
true
umount
uname
uncompress
vdir
wdctl
which
ypdomainname
zcat
zcmp
zdiff
zegrep
zfgrep
zforce
zgrep
zless
zmore
znew

/usr/bin:
[
2to3
2to3-2.7
2to3-3.5
aclocal
aclocal-1.15
addpart
addr2line
apropos
apt
apt-cache
apt-cdrom
apt-config
apt-get
apt-key
apt-mark
ar
arch
as
autoconf
autoheader
autom4te
automake
automake-1.15
autopoint
autoreconf
autoscan
autoupdate
awk
b2sum
base32
base64
basename
bashbug
bc
bin2obj
bin2obj-3.0.0
broadwayd
bsd-from
bsd-write
bugpoint
bugpoint-3.8
c++
c2ph
c89
c89-gcc
c99
c99-gcc
cal
calendar
captoinfo
catchsegv
catman
cc
c++filt
chage
chardet
chardet3
chardetect
chardetect3
chattr
chcon
chfn
chicken
chicken-bug
chicken-install
chicken-profile
chicken-status
chicken-uninstall
chmcmd
chmcmd-3.0.0
chmls
chmls-3.0.0
chrt
chsh
cksum
clear
clear_console
clips
clisp
clisp-link
cmp
col
colcrt
colrm
column
comm
compose
corelist
cpan
cpan5.24-x86_64-linux-gnu
cpp
cpp-6
crc32
createfontdatachunk
createfontdatachunk.py
c_rehash
csc
csi
csplit
cut
data2inc
data2inc-3.0.0
dbus-cleanup-sockets
dbus-daemon
dbus-launch
dbus-monitor
dbus-run-session
dbus-send
dbus-update-activation-environment
dbus-uuidgen
debconf
debconf-apt-progress
debconf-communicate
debconf-copydb
debconf-escape
debconf-gettextize
debconf-set-selections
debconf-show
debconf-updatepo
deb-systemd-helper
deb-systemd-invoke
delp
delp-3.0.0
delpart
dh
dh_auto_build
dh_auto_clean
dh_auto_configure
dh_auto_install
dh_autoreconf
dh_autoreconf_clean
dh_auto_test
dh_autotools-dev_restoreconfig
dh_autotools-dev_updateconfig
dh_bugfiles
dh_builddeb
dh_clean
dh_compress
dh_fixperms
dh_gconf
dh_gencontrol
dh_icons
dh_install
dh_installcatalogs
dh_installchangelogs
dh_installcron
dh_installdeb
dh_installdebconf
dh_installdirs
dh_installdocs
dh_installemacsen
dh_installexamples
dh_installgsettings
dh_installifupdown
dh_installinfo
dh_installinit
dh_installlogcheck
dh_installlogrotate
dh_installman
dh_installmanpages
dh_installmenu
dh_installmime
dh_installmodules
dh_installpam
dh_installppp
dh_installudev
dh_installwm
dh_installxfonts
dh_installxmlcatalogs
dh_link
dh_lintian
dh_listpackages
dh_makeshlibs
dh_md5sums
dh_movefiles
dh_numpy
dh_numpy3
dh_perl
dh_prep
dh_pypy
dh_python2
dh_python3
dh_shlibdeps
dh_strip
dh_strip_nondeterminism
dh_swi_prolog
dh_systemd_enable
dh_systemd_start
dh_testdir
dh_testroot
dh_ucf
dh_update_autotools_config
dh_usrlocal
diff
diff3
dircolors
dirmngr
dirmngr-client
dirname
dpkg
dpkg-architecture
dpkg-buildflags
dpkg-buildpackage
dpkg-checkbuilddeps
dpkg-deb
dpkg-distaddfile
dpkg-divert
dpkg-genbuildinfo
dpkg-genchanges
dpkg-gencontrol
dpkg-gensymbols
dpkg-maintscript-helper
dpkg-mergechangelogs
dpkg-name
dpkg-parsechangelog
dpkg-query
dpkg-scanpackages
dpkg-scansources
dpkg-shlibdeps
dpkg-source
dpkg-split
dpkg-statoverride
dpkg-trigger
dpkg-vendor
drracket
du
dwp
easy_install
easy_install3
edit
elfedit
enc2xs
encguess
enhancer
enhancer.py
env
envsubst
eqn
erb
erb2.3
expand
expiry
explode
explode.py
expr
f2py
f2py2.7
f2py3
f2py3.5
factor
faillog
faked-sysv
faked-tcp
fakeroot
fakeroot-sysv
fakeroot-tcp
fallocate
fc-cache
fc-cat
fc-list
fc-match
fc-pattern
fc-query
fc-scan
fc-validate
fd2pascal-3.0.0
file
file-rename
find
flock
fmt
fold
fpc
fpc-3.0.0
fpc-depends
fpc-depends-3.0.0
fpcjres-3.0.0
fpclasschart
fpclasschart-3.0.0
fpcmake
fpcmake-3.0.0
fpcmkcfg-3.0.0
fpcres
fpcres-3.0.0
fpcsubst
fpcsubst-3.0.0
fpdoc
fpdoc-3.0.0
fppkg
fppkg-3.0.0
fprcp
fprcp-3.0.0
from
funzip
g++
g++-6
gawk
gcc
gcc-6
gcc-ar
gcc-ar-6
gcc-nm
gcc-nm-6
gcc-ranlib
gcc-ranlib-6
gcov
gcov-6
gcov-tool
gcov-tool-6
gem
gem2.3
gencat
geqn
getconf
getent
getopt
gettext
gettextize
gettext.sh
gforth
gforth-0.7.3
gforth-fast
gforth-fast-0.7.3
gforth-itc
gforth-itc-0.7.3
gforthmi
gforthmi-0.7.3
gifmaker
gifmaker.py
glxdemo
glxgears
glxheads
glxinfo
gnuplot
gnuplot-qt
gold
gpasswd
gpg
gpg-agent
gpgconf
gpg-connect-agent
gpgparsemail
gpgsplit
gpgv
gpg-zip
gpic
gplc
gprof
gprolog
grab_vcsa-3.0.0
gracket
gracket-text
groff
grog
grops
grotty
groups
gst
gst-convert
gst-doc
gst-load
gst-package
gst-profile
gst-reload
gst-remote
gst-sunit
gtbl
gtk-builder-tool
gtk-launch
gtk-query-settings
gtk-update-icon-cache
guile
guile-2.0
h2pas
h2pas-3.0.0
h2paspp
h2paspp-3.0.0
h2ph
h2xs
hd
head
hexdump
hexgplc
hostid
i386
iconv
id
ifnames
ifpc
ifpc-3.0.0
igawk
infocmp
infotocap
install
instantfpc
instmodsh
ionice
ipcmk
ipcrm
ipcs
irb
irb2.3
ischroot
join
js24
json_pp
kbxutil
killall
last
lastb
lastlog
lcf
ld
ld.bfd
ldd
ld.gold
ldrdf
lexgrog
libnetcfg
libtoolize
libwacom-list-local-devices
line
link
linux32
linux64
llc
llc-3.8
lli
lli-3.8
llvm-ar
llvm-ar-3.8
llvm-as
llvm-as-3.8
llvm-bcanalyzer
llvm-bcanalyzer-3.8
llvm-config
llvm-config-3.8
llvm-cov
llvm-cov-3.8
llvm-c-test-3.8
llvm-cxxdump-3.8
llvm-diff
llvm-diff-3.8
llvm-dis
llvm-dis-3.8
llvm-dsymutil-3.8
llvm-dwarfdump
llvm-dwarfdump-3.8
llvm-dwp-3.8
llvm-extract
llvm-extract-3.8
llvm-lib-3.8
llvm-link
llvm-link-3.8
llvm-lto-3.8
llvm-mc
llvm-mc-3.8
llvm-mcmarkup-3.8
llvm-nm
llvm-nm-3.8
llvm-objdump
llvm-objdump-3.8
llvm-pdbdump-3.8
llvm-PerfectShuffle-3.8
llvm-profdata-3.8
llvm-ranlib
llvm-ranlib-3.8
llvm-readobj-3.8
llvm-rtdyld
llvm-rtdyld-3.8
llvm-size
llvm-size-3.8
llvm-split-3.8
llvm-stress-3.8
llvm-symbolizer-3.8
llvm-tblgen
llvm-tblgen-3.8
locale
localedef
logger
logname
look
lorder
lsattr
lscpu
lsipc
lslocks
lslogins
lsns
lspgpot
lua5.3
luac5.3
lzcat
lzcmp
lzdiff
lzegrep
lzfgrep
lzgrep
lzless
lzma
lzmainfo
lzmore
m4
ma2asm
macho-dump
make
make-first-existing-target
makeskel
makeskel-3.0.0
man
mandb
manpath
mawk
mcookie
md5sum
md5sum.textutils
mesg
migrate-pubring-from-classic-gpg
mkfifo
moar
mred
mred-text
msgattrib
msgcat
msgcmp
msgcomm
msgconv
msgen
msgexec
msgfilter
msgfmt
msggrep
msginit
msgmerge
msgunfmt
msguniq
mtrace
mzc
mzpp
mzscheme
mztext
namei
nasm
nawk
ncal
ncursesw5-config
ndisasm
neqn
newgrp
ngettext
nice
nl
nm
nohup
nproc
nqp
nqp-m
nroff
nsenter
numfmt
obj2yaml
obj2yaml-3.8
objcopy
objdump
od
openssl
opt
opt-3.8
pager
painter
painter.py
partx
pas2fpm-3.0.0
pas2jni-3.0.0
pas2ut-3.0.0
passwd
paste
patch
pathchk
pc
pcre-config
pdb
pdb2.7
pdb3
pdb3.5
pdepend.phar
pdf-slatex
peekfd
perl
perl5.24.1
perl5.24-x86_64-linux-gnu
perl6
perl6-debug-m
perl6-gdb-m
perl6-m
perl6-valgrind-m
perlbug
perldoc
perlivp
perlthanks
pg
phar
phar7.1
phar.phar
phar.phar7.1
php
php7.1
phpcpd.phar
phpcs.phar
phploc.phar
phpmd.phar
phpunit.phar
pic
picolisp
piconv
pike
pike8.0
pil
pilconvert
pilconvert.py
pildriver
pildriver.py
pilfile
pilfile.py
pilfont
pilfont.py
pilprint
pilprint.py
pinentry
pinentry-curses
pinky
pip
pip2
pip3
pl2pm
pl2wam
player
player.py
pldd
plex
plex-3.0.0
plt-games
plt-help
plt-r5rs
plt-r6rs
plt-web-server
po2debconf
pod2html
pod2man
pod2text
pod2usage
podchecker
podebconf-display-po
podebconf-report-po
podselect
postw32
postw32-3.0.0
ppcx64
ppcx64-3.0.0
ppdep
ppdep-3.0.0
ppudump
ppudump-3.0.0
ppufiles
ppufiles-3.0.0
ppumove
ppumove-3.0.0
pr
preconv
prename
prepend.cli
print
printenv
printerbanner
printf
prlimit
prolog
prove
prtstat
pstree
pstree.x11
pstruct
ptar
ptardiff
ptargrep
ptop
ptop-3.0.0
ptx
py3clean
py3compile
py3versions
pyacc
pyacc-3.0.0
pybuild
pyclean
pycompile
pydoc
pydoc2.7
pydoc3
pydoc3.5
pygettext
pygettext2.7
pygettext3
pygettext3.5
pypy
pypyclean
pypycompile
python
python2
python2.7
python2.7-config
python2-config
python3
python3.5
python3.5-config
python3.5m
python3.5m-config
python3-config
python3m
python3m-config
python-config
pyversions
racket
raco
rake
ranlib
rdf2bin
rdf2com
rdf2ihx
rdf2ith
rdf2srec
rdfdump
rdflib
rdoc
rdoc2.3
rdx
readelf
realpath
recode-sr-latin
relpath
relpath-3.0.0
rename
rename.ul
renice
reset
resizepart
rev
rgrep
ri
ri2.3
rmcvsdir
rmcvsdir-3.0.0
rpcgen
rstconv
rstconv-3.0.0
ruby
ruby2.3
runcon
run-mailcap
savelog
sbcl
scribble
script
scriptreplay
sdiff
see
select-editor
sensible-browser
sensible-editor
sensible-pager
seq
setarch
setsid
setterm
setup-plt
sg
sha1sum
sha224sum
sha256sum
sha384sum
sha512sum
shasum
shred
shuf
size
slatex
slideshow
soelim
sort
sotruss
splain
split
sprof
sqldiff
sqlite3
stalin
stat
stdbuf
strings
strip
sum
swindle
swipl
swipl-ld
swipl-rc
symcryptrun
tabs
tac
tail
taskset
tbl
tclsh
tclsh8.6
tee
test
thresholder
thresholder.py
tic
timeout
toe
touch
tput
tr
troff
truncate
tset
tsort
tty
tzselect
ucf
ucfq
ucfr
ul
unexpand
uniq
unitdiff
unitdiff-3.0.0
unlambda
unlink
unlzma
unshare
unxz
unzip
unzipsfx
update-alternatives
update-mime-database
update-mime-database.real
users
utmpdump
verify-uselistorder
verify-uselistorder-3.8
viewer
viewer.py
vmgen
vmgen-0.7.3
wall
wam2ma
watchgnupg
wc
wget
whatis
whereis
which
who
whoami
write
X11
x86_64
x86_64-linux-gnu-addr2line
x86_64-linux-gnu-ar
x86_64-linux-gnu-as
x86_64-linux-gnu-c++filt
x86_64-linux-gnu-cpp
x86_64-linux-gnu-cpp-6
x86_64-linux-gnu-dwp
x86_64-linux-gnu-elfedit
x86_64-linux-gnu-g++
x86_64-linux-gnu-g++-6
x86_64-linux-gnu-gcc
x86_64-linux-gnu-gcc-6
x86_64-linux-gnu-gcc-ar
x86_64-linux-gnu-gcc-ar-6
x86_64-linux-gnu-gcc-nm
x86_64-linux-gnu-gcc-nm-6
x86_64-linux-gnu-gcc-ranlib
x86_64-linux-gnu-gcc-ranlib-6
x86_64-linux-gnu-gcov
x86_64-linux-gnu-gcov-6
x86_64-linux-gnu-gcov-tool
x86_64-linux-gnu-gcov-tool-6
x86_64-linux-gnu-gprof
x86_64-linux-gnu-ld
x86_64-linux-gnu-ld.bfd
x86_64-linux-gnu-ld.gold
x86_64-linux-gnu-nm
x86_64-linux-gnu-objcopy
x86_64-linux-gnu-objdump
x86_64-linux-gnu-python2.7-config
x86_64-linux-gnu-python3.5-config
x86_64-linux-gnu-python3.5m-config
x86_64-linux-gnu-python3-config
x86_64-linux-gnu-python3m-config
x86_64-linux-gnu-python-config
x86_64-linux-gnu-ranlib
x86_64-linux-gnu-readelf
x86_64-linux-gnu-size
x86_64-linux-gnu-strings
x86_64-linux-gnu-strip
xargs
xdg-user-dir
xdg-user-dirs-update
xgettext
xpce
xpce-client
xsubpp
xz
xzcat
xzcmp
xzdiff
xzegrep
xzfgrep
xzgrep
xzless
xzmore
yaml2obj
yaml2obj-3.8
yes
zdump
zip
zipcloak
zipdetails
zipgrep
zipinfo
zipnote
zipsplit