UNIX PROGRAMMER'S MANUAL
K. Thompson
D. M. Ritchie
November 3, 1971
INTRODUCTION
This manual gives complete descriptions of all the publicly
available features of UNIX. It provides neither a general over-
view (see "The UNIX Time-sharing System" for that) nor details of
the implementation of the system (which remain to be disclosed).
Within the area it surveys, this manual attempts to be as com-
plete and timely as possible. A conscious decision was made to
describe each program in exactly the state it was in at the time
its manual section was prepared. In particular, the desire to
describe something as it should be, not as it is, was resisted.
Inevitably, this means that many sections will soon be out of
date. (The rate of change of the system is so great that a dis-
mayingly large number of early sections had to be modified while
the rest were being written. The unbounded effort required to
stay up-to-date is best indicated by the fact that several of the
programs described were written specifically to aid in prepara-
tion of this manual!)
This manual is divided into seven sections:
I. Commands
II. System calls
III. Subroutines
IV. Special files
V. File formats
VI. User-maintained programs
VII. Miscellaneous
Commands are programs intended to be invoked directly by the
user, in contradistinction to subroutines, which are intended to
be called by the user's programs. Commands generally reside in
directory /bin (for binary programs). This directory is searched
automatically by the command line interpreter. Some programs
classified as commands are located elsewhere; this fact is indi-
cated in the appropriate sections.
System calls are entries into the UNIX supervisor. In assembly
language, they are coded with the use of the opcode "sys", a syn-
onym for the trap instruction.
The special files section discusses the characteristics of each
system "file" which actually refers to an I/O device.
The file formats section documents the structure of particular
kinds of files; for example, the form of the output of the loader
and assembler is given. Excluded are files used by only one com-
mand, for example the assembler's intermediate files.
User-maintained programs are not considered part of the UNIX sys-
tem, and the principal reason for listing them is o indicate
their existence without necessarily giving a complte description.
The author should be consulted for information.
The miscellaneous section gathers odds and ends.
Each section consists of a number of independent entries of a
page or so each. The name of the entry is in the upper right
corner of its pages, its preparation date in the upper left. En-
tries within each section are alphabetized. It was thought bet-
ter to avoid running page numbers, since it is hoped that the
manual will be updated frequently.
All entries have a common format.
The name section repeats the entry name and gives a very
short description of its purpose.
The synopsis summarizes the use of the program being de-
scribed. A few conventions are used, particularly in the
Commands section:
Underlined words are considered literals, and are typed
just as they appear.
Square brackets ([]) around an argument indicate that the
argument is optional. When an argument is given as
"name", it always refers to a file name.
Ellipses "..." are used to show that the previous
argument-prototype may be repeated.
A final convention is used by the commands themselves.
An argument beginning with a minus sign "-" is often tak-
en to mean some sort of flag argument even if it appears
in a position where a file name could appear. Therefore,
it is unwise to have files whose names begin with "-".
The description section discusses in detail the subject at
hand.
The files section gives the names of files which are built
into the program.
A see also section gives pointers to related information.
A diagnostics section discusses the diagnostics that may be
produced. This section tends to be as terse as the diagnos-
tics themselves.
The bugs section gives known bugs and sometimes deficien-
cies. Occasionally also the suggested fix is described.
The owner section gives the name of the person or persons to
be consulted in case of difficulty. The rule has been that
the last one to modify something owns it, so the owner is
not necessarily the author. The owner's initials stand for:
ken K. Thompson
dmr D. M. Ritchie
jfo J. F. Ossanna
rhm R. Morris
These three-character names also happen to be UNIX user
ID's, so messages may be transmitted by the mail command or,
if the addressee is logged in, by write.
At the beginning of this document is a table of contents, orga-
nized by section and alphabetically within each section. There
is also a permuted index derived from the table of contents.
Within each index entry, the title of the writeup to which it
refers is followed by the appropriate section number in parenthe-
ses. This fact is important because there is considerable name
duplication among the sections, arising principally from commands
which exist only to exercise a particular system call.
This manual was prepared using the UNIX text editor ed and the
formatting program roff.
TABLE OF CONTENTS
I. COMMANDS
ar ........................... archive (combine) files
as ........................... assembler
b ............................ compile B program
bas .......................... BASIC dialect
bcd .......................... convert ASCII to BCD
boot ......................... reboot system
cat .......................... concatenate (or print) files
chdir ........................ change working directory
check ........................ check consistency of file system
chmod ........................ change access mode of files
chown ........................ change owner of files
cmp .......................... compare file contents
cp ........................... copy file
date ......................... get date and time of day
db ........................... symbolic debugger
dbppt ........................ write binary paper tape
dc ........................... desk calculator
df ........................... find free disk space
dsw .......................... delete files interactively
dtf .......................... format DECtape
du ........................... find disk usage
ed ........................... text editor
find ......................... find file with given name
for .......................... compile Fortran program
form ......................... generate form letter
hup .......................... hang up typewriter
lbppt ........................ read binary paper tape
ld ........................... link editor (loader)
ln ........................... link to file
ls ........................... list contents of directory
mail ......................... send mail to another user
mesg ......................... permit or deny messages
mkdir ........................ create directory
mkfs ......................... initialize file system
mount ........................ mount removable file system
mv ........................... move or rename file
nm ........................... print namelist
od ........................... octal dump of file
pr ........................... print file with headings
rew .......................... rewind DECtape
rkd .......................... dump disk to tape
rkf .......................... format RK disk
rkl .......................... load disk from tape
rm ........................... remove (delete) file
rmdir ........................ remove (delete) directory
roff ......................... format text for printing
sdate ........................ adjust date and time
sh ........................... command interpreter
stat ......................... get file status
strip ........................ remove symbols, relocation bits
su ........................... become super-user
sum .......................... sum file
tap .......................... manipulate DECtape
tm ........................... get time information
tty .......................... find name of terminal
type ......................... print file page-by-page
umount ....................... dismount removable file system
un ........................... find undefined symbols
wc ........................... get (English) word count
who .......................... who is on the system
write ........................ write to another user
II. SYSTEM CALLS
break ........................ set program break
cemt ......................... catch EMT traps
chdir ........................ change working directory
chmod ........................ change mode of file
chown ........................ change owner of file
close ........................ close open file
creat ........................ create file
exec ......................... execute program file
exit ......................... terminate execution
fork ......................... create new process
fstat ........................ status of open file
getuid ....................... get user ID
gtty ......................... get typewriter mode
ilgins ....................... catch illegal instruction trap
intr ......................... catch or inhibit interrupts
link ......................... link to file
mkdir ........................ create directory
mount ........................ mount file system
open ......................... open file
quit ......................... catch or inhibit quits
read ......................... read file
rele ......................... release processor
seek ......................... move read or write pointer
setuid ....................... set user ID
smdate ....................... set date modified of file
stat ......................... get file status
stime ........................ set system time
stty ......................... set mode of typewriter
tell ......................... find read or write pointer
time ......................... get time of year
umount ....................... dismount file system
unlink ....................... remove (delete) file
wait ......................... wait for process
write ........................ write file
III. SUBROUTINES
atof ......................... convert ASCII to floating
atoi ......................... convert ASCII to integer
ctime ........................ convert time to ASCII
exp .......................... exponential function
fptrap ....................... floating-point simulator
ftoa ......................... convert floating to ASCII
get .......................... get character
itoa ......................... convert integer to ASCII
log .......................... logarithm base e
mesg ......................... print string on typewriter
ptime ........................ print time
putc ......................... write character or word
sin .......................... sine, cosine
switch ....................... transfer depending on value
IV. SPECIAL FILES
mem .......................... core memory as file
ppt .......................... punched paper tape
rf0 .......................... RF disk file
rk0 .......................... RK disk file
tap0,...,tap7 ................ DECtape file
tty .......................... console typewriter
tty0,...,tty5 ................ remote typewriter
V. FILE FORMATS
a.out ........................ assembler and loader output
archive ...................... archive file
bppt ......................... binary paper tape format
core ......................... core image file
directory .................... directory format
file system .................. file system format
passwd ....................... password file
uids ......................... map names to user ID's
utmp ......................... logged-in user information
VI. USER MAINTAINED PROGRAMS
basic ........................ DEC supplied BASIC
bj ........................... the game of blackjack
cal .......................... print calender
chess ........................ the game of chess
das .......................... disassembler
dli .......................... load DEC binary paper tapes
dpt .......................... read DEC ASCII paper tapes
moo .......................... the game of MOO
sort ......................... sort a file
ttt .......................... the game of tic-tac-toe
VII. MISCELLANEOUS
as2 .......................... assembler's pass 2
ascii ........................ map of ASCII
ba ........................... B assembler
bc ........................... B compiler
bilib ........................ B interpreter library
bproc ........................ boot procedure
brt1,brt2 .................... B start and finish
f1,f2,f3,f4 .................. Fortran compiler passes
glob ......................... argument expander
init ......................... initializer process
kbd .......................... map of TTY 37 keyboard
liba ......................... standard assembly-language library
libb ......................... standard B library
libf ......................... standard Fortran library
login, logout ................ logging on and logging off the system
msh .......................... mini Shell
suftab ....................... roff's suffix table
tabs ......................... set tab stops on typewriter
INDEX
as2(VII): assembler's pass 2
kbd(VII): map of TTY 37 keyboard
chmod(I): change access mode of files
sdate(I): adjust date and time
mail(I): send mail to another user
write(I): write to another user
a.out(V): assembler and loader output
ar(I): archive (combine) files
archive(V): archive file
archive(V): archive file
glob(VII): argument expander
ar(I): archive (combine) files
as2(VII): assembler's pass 2
dpt(VI): read DEC ASCII paper tapes
bcd(I): convert ASCII to BCD
atof(III): convert ASCII to floating
atoi(III): convert ASCII to integer
ascii(VII): map of ASCII
ctime(III): convert time to ASCII
ftoa(III): convert floating to ASCII
itoa(III): convert integer to ASCII
ascii(VII): map of ASCII
as(I): assembler
a.out(V): assembler and loader output
as(I): assembler
ba(VII): B assembler
as2(VII): assembler's pass 2
liba(VII): standard assembly-language library
atof(III): convert ASCII to floating
atoi(III): convert ASCII to integer
ba(VII): B assembler
bc(VII): B compiler
bilib(VII): B interpreter library
libb(VII): standard B library
b(I): compile B program
brt1,brt2(VII): B start and finish
log(III): logarithm base e
bas(I): BASIC dialect
bas(I): BASIC dialect
basic(VI): DEC supplied BASIC
basic(VI): DEC supplied BASIC
ba(VII): B assembler
bcd(I): convert ASCII to BCD
bcd(I): convert ASCII to BCD
bc(VII): B compiler
su(I): become super-user
b(I): compile B program
bilib(VII): B interpreter library
bppt(V): binary paper tape format
dbppt(I): write binary paper tape
lbppt(I): read binary paper tape
dli(VI): load DEC binary paper tapes
strip(I): remove symbols, relocation bits
bj(VI): the game of blackjack
bj(VI): the game of blackjack
bproc(VII): boot procedure
boot(I): reboot system
bppt(V): binary paper tape format
bproc(VII): boot procedure
break(II): set program break
break(II): set program break
brt1,brt2(VII): B start and finish
dc(I): desk calculator
cal(VI): print calender
cal(VI): print calender
cemt(II): catch EMT traps
ilgins(II): catch illegal instruction trap
intr(II): catch or inhibit interrupts
quit(II): catch or inhibit quits
cat(I): concatenate (or print) files
cemt(II): catch EMT traps
chmod(I): change access mode of files
chmod(II): change mode of file
chown(II): change owner of file
chown(I): change owner of files
chdir(I): change working directory
chdir(II): change working directory
putc(III): write character or word
get(III): get character
chdir(I): change working directory
chdir(II): change working directory
check(I): check consistency of file system
check(I): check consistency of file system
chess(VI): the game of chess
chess(VI): the game of chess
chmod(I): change access mode of files
chmod(II): change mode of file
chown(I): change owner of files
chown(II): change owner of file
close(II): close open file
close(II): close open file
cmp(I): compare file contents
ar(I): archive (combine) files
sh(I): command interpreter
cmp(I): compare file contents
b(I): compile B program
for(I): compile Fortran program
f1,f2,f3,f4(VII): Fortran compiler passes
bc(VII): B compiler
cat(I): concatenate (or print) files
check(I): check consistency of file system
tty(IV): console typewriter
ls(I): list contents of directory
cmp(I): compare file contents
bcd(I): convert ASCII to BCD
atof(III): convert ASCII to floating
atoi(III): convert ASCII to integer
ftoa(III): convert floating to ASCII
itoa(III): convert integer to ASCII
ctime(III): convert time to ASCII
cp(I): copy file
core(V): core image file
mem(IV): core memory as file
core(V): core image file
sin(III): sine, cosine
wc(I): get (English) word count
cp(I): copy file
mkdir(I): create directory
mkdir(II): create directory
creat(II): create file
fork(II): create new process
creat(II): create file
ctime(III): convert time to ASCII
das(VI): disassembler
date(I): get date and time of day
sdate(I): adjust date and time
smdate(II): set date modified of file
date(I): get date and time of day
date(I): get date and time of day
db(I): symbolic debugger
dbppt(I): write binary paper tape
dc(I): desk calculator
db(I): symbolic debugger
dpt(VI): read DEC ASCII paper tapes
dli(VI): load DEC binary paper tapes
basic(VI): DEC supplied BASIC
tap0,...,tap7(IV): DECtape file
dtf(I): format DECtape
rew(I): rewind DECtape
tap(I): manipulate DECtape
rmdir(I): remove (delete) directory
rm(I): remove (delete) file
dsw(I): delete files interactively
unlink(II): remove (delete) file
mesg(I): permit or deny messages
switch(III): transfer depending on value
dc(I): desk calculator
df(I): find free disk space
bas(I): BASIC dialect
directory(V): directory format
chdir(I): change working directory
chdir(II): change working directory
ls(I): list contents of directory
mkdir(I): create directory
mkdir(II): create directory
rmdir(I): remove (delete) directory
directory(V): directory format
das(VI): disassembler
rf0(IV): RF disk file
rk0(IV): RK disk file
rkl(I): load disk from tape
df(I): find free disk space
rkd(I): dump disk to tape
du(I): find disk usage
rkf(I): format RK disk
umount(II): dismount file system
umount(I): dismount removable file system
dli(VI): load DEC binary paper tapes
dpt(VI): read DEC ASCII paper tapes
dsw(I): delete files interactively
dtf(I): format DECtape
du(I): find disk usage
rkd(I): dump disk to tape
od(I): octal dump of file
ed(I): text editor
ld(I): link editor (loader)
ed(I): text editor
log(III): logarithm base e
cemt(II): catch EMT traps
wc(I): get (English) word count
exec(II): execute program file
exec(II): execute program file
exit(II): terminate execution
exit(II): terminate execution
glob(VII): argument expander
exp(III): exponential function
exp(III): exponential function
f1,f2,f3,f4(VII): Fortran compiler passes
cmp(I): compare file contents
type(I): print file page-by-page
stat(I): get file status
stat(II): get file status
file system(V): file system format
check(I): check consistency of file system
mkfs(I): initialize file system
mount(I): mount removable file system
mount(II): mount file system
umount(I): dismount removable file system
umount(II): dismount file system
file system(V): file system format
find(I): find file with given name
pr(I): print file with headings
archive(V): archive file
chmod(II): change mode of file
chown(II): change owner of file
close(II): close open file
core(V): core image file
cp(I): copy file
creat(II): create file
exec(II): execute program file
fstat(II): status of open file
link(II): link to file
ln(I): link to file
mem(IV): core memory as file
mv(I): move or rename file
od(I): octal dump of file
open(II): open file
passwd(V): password file
read(II): read file
rf0(IV): RF disk file
rk0(IV): RK disk file
rm(I): remove (delete) file
dsw(I): delete files interactively
ar(I): archive (combine) files
cat(I): concatenate (or print) files
chmod(I): change access mode of files
chown(I): change owner of files
smdate(II): set date modified of file
sort(VI): sort a file
sum(I): sum file
tap0,...,tap7(IV): DECtape file
unlink(II): remove (delete) file
write(II): write file
du(I): find disk usage
find(I): find file with given name
df(I): find free disk space
tty(I): find name of terminal
tell(II): find read or write pointer
un(I): find undefined symbols
find(I): find file with given name
brt1,brt2(VII): B start and finish
ftoa(III): convert floating to ASCII
atof(III): convert ASCII to floating
fptrap(III): floating-point simulator
for(I): compile Fortran program
fork(II): create new process
form(I): generate form letter
dtf(I): format DECtape
rkf(I): format RK disk
roff(I): format text for printing
bppt(V): binary paper tape format
directory(V): directory format
file system(V): file system format
form(I): generate form letter
f1,f2,f3,f4(VII): Fortran compiler passes
libf(VII): standard Fortran library
for(I): compile Fortran program
fptrap(III): floating-point simulator
df(I): find free disk space
rkl(I): load disk from tape
fstat(II): status of open file
ftoa(III): convert floating to ASCII
exp(III): exponential function
bj(VI): the game of blackjack
chess(VI): the game of chess
moo(VI): the game of MOO
ttt(VI): the game of tic-tac-toe
form(I): generate form letter
get(III): get character
date(I): get date and time of day
wc(I): get (English) word count
stat(I): get file status
stat(II): get file status
tm(I): get time information
time(II): get time of year
gtty(II): get typewriter mode
getuid(II): get user ID
get(III): get character
getuid(II): get user ID
find(I): find file with given name
glob(VII): argument expander
gtty(II): get typewriter mode
hup(I): hang up typewriter
pr(I): print file with headings
hup(I): hang up typewriter
getuid(II): get user ID
setuid(II): set user ID
uids(V): map names to user ID's
ilgins(II): catch illegal instruction trap
ilgins(II): catch illegal instruction trap
core(V): core image file
tm(I): get time information
utmp(V): logged-in user information
intr(II): catch or inhibit interrupts
quit(II): catch or inhibit quits
mkfs(I): initialize file system
init(VII): initializer process
init(VII): initializer process
ilgins(II): catch illegal instruction trap
itoa(III): convert integer to ASCII
atoi(III): convert ASCII to integer
dsw(I): delete files interactively
bilib(VII): B interpreter library
sh(I): command interpreter
intr(II): catch or inhibit interrupts
intr(II): catch or inhibit interrupts
itoa(III): convert integer to ASCII
kbd(VII): map of TTY 37 keyboard
kbd(VII): map of TTY 37 keyboard
lbppt(I): read binary paper tape
ld(I): link editor (loader)
form(I): generate form letter
liba(VII): standard assembly-language library
libb(VII): standard B library
libf(VII): standard Fortran library
bilib(VII): B interpreter library
liba(VII): standard assembly-language library
libb(VII): standard B library
libf(VII): standard Fortran library
ld(I): link editor (loader)
link(II): link to file
ln(I): link to file
link(II): link to file
ls(I): list contents of directory
ln(I): link to file
dli(VI): load DEC binary paper tapes
rkl(I): load disk from tape
a.out(V): assembler and loader output
ld(I): link editor (loader)
log(III): logarithm base e
utmp(V): logged-in user information
log(III): logarithm base e
ls(I): list contents of directory
mail(I): send mail to another user
mail(I): send mail to another user
tap(I): manipulate DECtape
uids(V): map names to user ID's
ascii(VII): map of ASCII
kbd(VII): map of TTY 37 keyboard
mem(IV): core memory as file
mem(IV): core memory as file
mesg(I): permit or deny messages
mesg(III): print string on typewriter
mesg(I): permit or deny messages
mkdir(I): create directory
mkdir(II): create directory
mkfs(I): initialize file system
chmod(II): change mode of file
chmod(I): change access mode of files
stty(II): set mode of typewriter
gtty(II): get typewriter mode
smdate(II): set date modified of file
moo(VI): the game of MOO
moo(VI): the game of MOO
mount(II): mount file system
mount(I): mount removable file system
mount(I): mount removable file system
mount(II): mount file system
mv(I): move or rename file
seek(II): move read or write pointer
mv(I): move or rename file
tty(I): find name of terminal
find(I): find file with given name
nm(I): print namelist
uids(V): map names to user ID's
fork(II): create new process
nm(I): print namelist
od(I): octal dump of file
od(I): octal dump of file
close(II): close open file
fstat(II): status of open file
open(II): open file
open(II): open file
cat(I): concatenate (or print) files
a.out(V): assembler and loader output
chown(II): change owner of file
chown(I): change owner of files
type(I): print file page-by-page
bppt(V): binary paper tape format
dbppt(I): write binary paper tape
lbppt(I): read binary paper tape
ppt(IV): punched paper tape
dli(VI): load DEC binary paper tapes
dpt(VI): read DEC ASCII paper tapes
as2(VII): assembler's pass 2
f1,f2,f3,f4(VII): Fortran compiler passes
passwd(V): password file
passwd(V): password file
mesg(I): permit or deny messages
seek(II): move read or write pointer
tell(II): find read or write pointer
ppt(IV): punched paper tape
pr(I): print file with headings
cal(VI): print calender
type(I): print file page-by-page
pr(I): print file with headings
cat(I): concatenate (or print) files
nm(I): print namelist
mesg(III): print string on typewriter
ptime(III): print time
roff(I): format text for printing
bproc(VII): boot procedure
fork(II): create new process
init(VII): initializer process
rele(II): release processor
wait(II): wait for process
break(II): set program break
exec(II): execute program file
b(I): compile B program
for(I): compile Fortran program
ptime(III): print time
ppt(IV): punched paper tape
putc(III): write character or word
quit(II): catch or inhibit quits
quit(II): catch or inhibit quits
lbppt(I): read binary paper tape
dpt(VI): read DEC ASCII paper tapes
read(II): read file
seek(II): move read or write pointer
tell(II): find read or write pointer
read(II): read file
boot(I): reboot system
rele(II): release processor
rele(II): release processor
strip(I): remove symbols, relocation bits
tty0,...,tty5(IV): remote typewriter
mount(I): mount removable file system
umount(I): dismount removable file system
rmdir(I): remove (delete) directory
rm(I): remove (delete) file
unlink(II): remove (delete) file
strip(I): remove symbols, relocation bits
mv(I): move or rename file
rew(I): rewind DECtape
rew(I): rewind DECtape
rf0(IV): RF disk file
rf0(IV): RF disk file
rk0(IV): RK disk file
rkf(I): format RK disk
rk0(IV): RK disk file
rkd(I): dump disk to tape
rkf(I): format RK disk
rkl(I): load disk from tape
rmdir(I): remove (delete) directory
rm(I): remove (delete) file
roff(I): format text for printing
sdate(I): adjust date and time
seek(II): move read or write pointer
mail(I): send mail to another user
smdate(II): set date modified of file
stty(II): set mode of typewriter
break(II): set program break
stime(II): set system time
setuid(II): set user ID
setuid(II): set user ID
sh(I): command interpreter
fptrap(III): floating-point simulator
sin(III): sine, cosine
sin(III): sine, cosine
smdate(II): set date modified of file
sort(VI): sort a file
sort(VI): sort a file
df(I): find free disk space
liba(VII): standard assembly-language library
libb(VII): standard B library
libf(VII): standard Fortran library
brt1,brt2(VII): B start and finish
stat(I): get file status
stat(II): get file status
fstat(II): status of open file
stat(I): get file status
stat(II): get file status
stime(II): set system time
mesg(III): print string on typewriter
strip(I): remove symbols, relocation bits
stty(II): set mode of typewriter
su(I): become super-user
sum(I): sum file
sum(I): sum file
su(I): become super-user
basic(VI): DEC supplied BASIC
switch(III): transfer depending on value
db(I): symbolic debugger
strip(I): remove symbols, relocation bits
un(I): find undefined symbols
file system(V): file system format
stime(II): set system time
boot(I): reboot system
check(I): check consistency of file system
mkfs(I): initialize file system
mount(I): mount removable file system
mount(II): mount file system
umount(I): dismount removable file system
umount(II): dismount file system
file system(V): file system format
who(I): who is on the system
tap0,...,tap7(IV): DECtape file
bppt(V): binary paper tape format
dbppt(I): write binary paper tape
lbppt(I): read binary paper tape
ppt(IV): punched paper tape
rkd(I): dump disk to tape
rkl(I): load disk from tape
dli(VI): load DEC binary paper tapes
dpt(VI): read DEC ASCII paper tapes
tap(I): manipulate DECtape
tell(II): find read or write pointer
tty(I): find name of terminal
exit(II): terminate execution
ed(I): text editor
roff(I): format text for printing
ttt(VI): the game of tic-tac-toe
tm(I): get time information
date(I): get date and time of day
time(II): get time of year
ctime(III): convert time to ASCII
time(II): get time of year
ptime(III): print time
sdate(I): adjust date and time
stime(II): set system time
tm(I): get time information
switch(III): transfer depending on value
ilgins(II): catch illegal instruction trap
cemt(II): catch EMT traps
ttt(VI): the game of tic-tac-toe
kbd(VII): map of TTY 37 keyboard
tty0,...,tty5(IV): remote typewriter
tty(I): find name of terminal
tty(IV): console typewriter
type(I): print file page-by-page
gtty(II): get typewriter mode
hup(I): hang up typewriter
mesg(III): print string on typewriter
stty(II): set mode of typewriter
tty0,...,tty5(IV): remote typewriter
tty(IV): console typewriter
uids(V): map names to user ID's
umount(I): dismount removable file system
umount(II): dismount file system
un(I): find undefined symbols
un(I): find undefined symbols
unlink(II): remove (delete) file
du(I): find disk usage
getuid(II): get user ID
setuid(II): set user ID
uids(V): map names to user ID's
utmp(V): logged-in user information
mail(I): send mail to another user
write(I): write to another user
utmp(V): logged-in user information
switch(III): transfer depending on value
wait(II): wait for process
wait(II): wait for process
wc(I): get (English) word count
who(I): who is on the system
who(I): who is on the system
find(I): find file with given name
pr(I): print file with headings
wc(I): get (English) word count
putc(III): write character or word
chdir(I): change working directory
chdir(II): change working directory
dbppt(I): write binary paper tape
putc(III): write character or word
write(II): write file
seek(II): move read or write pointer
tell(II): find read or write pointer
write(I): write to another user
write(I): write to another user
write(II): write file
time(II): get time of year