This manual documents version 2.0.11 of the GNU shell utilities.
First of all, this manual is incomplete. The stty section, in
particular, needs substantial reorganization and additional explanatory
text before it will be up to the standard of other GNU manuals.
Explanatory text in general is lacking; the manual presently assumes you
pretty much know what to do, and just need to be reminded of how. Thus,
if you are interested, please get involved in improving this manual.
The entire GNU community will benefit.
Some of these programs are useful only when writing shell scripts; utilities like these are, in fact, the "language" of shell scripts (to a great extent). Others are occasionally useful interactively.
The GNU shell utilities are mostly compatible with the POSIX.2 standard.
Please report bugs to [email protected]. Remember
to include the version number, machine architecture, input files, and
any other information needed to reproduce the bug: your input, what you
expected, what you got, and why it is wrong. Diffs are welcome, but
please include a description of the problem as well, since this is
sometimes difficult to infer. See Bugs.
This manual was originally derived from the Unix man pages in the distribution, which were written by David MacKenzie and updated by Jim Meyering. What you are reading now is the authoritative documentation for these utilities; the man pages are no longer being maintained. François Pinard did the initial conversion to Texinfo format. Karl Berry did the indexing, some reorganization, and editing of the results. Richard Stallman contributed his usual invaluable insights to the overall process.
Certain options are available in all these programs. Rather than writing identical descriptions for each of the programs, they are described here. (In fact, every GNU program accepts (or should accept) these options.)
Many of these programs take arbitrary strings as arguments. In those
cases, --help and --version are taken as these options
only if there is one and exactly one command line argument.
--help
--version
First, a quote:
Our units of temporal measurement, from seconds on up to months, are so complicated, asymmetrical and disjunctive so as to make coherent mental reckoning in time all but impossible. Indeed, had some tyrannical god contrived to enslave our minds to time, to make it all but impossible for us to escape subjection to sodden routines and unpleasant surprises, he could hardly have done better than handing down our present system. It is like a set of trapezoidal building blocks, with no vertical or horizontal surfaces, like a language in which the simplest thought demands ornate constructions, useless particles and lengthy circumlocutions. Unlike the more successful patterns of language and science, which enable us to face experience boldly or at least level-headedly, our system of temporal calculation silently and persistently encourages our terror of time. ... It is as though architects had to measure length in feet, width in meters and height in ells; as though basic instruction manuals demanded a knowledge of five different languages. It is no wonder then that we often look into our own immediate past or future, last Tuesday or a week from Sunday, with feelings of helpless confusion. ...-- Robert Grudin, Time and the Art of Living.
This section describes the textual date representations that GNU
programs accept. These are the strings you, as a user, can supply as
arguments to the various programs. The C interface (via the
getdate function) is not described here.
Although the date syntax here can represent any possible time since zero A.D., computer integers are not big enough for such a (comparatively) long time. The earliest date semantically allowed on Unix systems is midnight, 1 January 1970 UCT.
A date is a string, possibly empty, containing many items separated by whitespace. The whitespace may be omitted when no ambiguity arises. The empty string means the beginning of today (i.e., midnight). Order of the items is immaterial. A date string may contain many flavors of items:
We describe each of these item types in turn, below.
A few numbers may be written out in words in most contexts. This is
most useful for specifying day of the week items or relative items (see
below). Here is the list: first for 1, next for 2,
third for 3, fourth for 4, fifth for 5,
sixth for 6, seventh for 7, eighth for 8,
ninth for 9, tenth for 10, eleventh for 11 and
twelfth for 12. Also, last means exactly -1.
When a month is written this way, it is still considered to be written numerically, instead of being "spelled in full"; this changes the allowed strings.
Alphabetic case is completely ignored in dates. Comments may be introduced between round parentheses, as long as included parentheses are properly nested. Hyphens not followed by a digit are currently ignored. Leading zeros on numbers are ignored.
A calendar date item specifies a day of the year. It is specified differently, depending on whether the month is specified numerically or literally. All these strings specify the same calendar date:
1972-09-24 # ISO 8601.
72-9-24 # Assume 19xx for 69 through 99,
# 20xx for 00 through 68.
72-09-24 # Leading zeros are ignored.
9/24/72 # Common U.S. writing.
24 September 1972
24 Sept 72 # September has a special abbreviation.
24 Sep 72 # Three-letter abbreviations always allowed.
Sep 24, 1972
24-sep-72
24sep72
The year can also be omitted. In this case, the last specified year is used, or the current year if none. For example:
9/24 sep 24
Here are the rules.
For numeric months, the ISO 8601 format
year-month-day is allowed, where year is
any positive number, month is a number between 01 and 12, and
day is a number between 01 and 31. A leading zero must be present
if a number is less than ten. If year is 68 or smaller, then 2000
is added to it; otherwise, if year is less than 100,
then 1900 is added to it. The construct
month/day/year, popular in the United States,
is accepted. Also month/day, omitting the year.
Literal months may be spelled out in full: January,
February, March, April, May, June,
July, August, September, October,
November or December. Literal months may be abbreviated
to their first three letters, possibly followed by an abbreviating dot.
It is also permitted to write Sept instead of September.
When months are written literally, the calendar date may be given as any of the following:
day month year day month month day year day-month-year
Or, omitting the year:
month day
A time of day item in date strings specifies the time on a given day. Here are some examples, all of which represent the same time:
20:02:0 20:02 8:02pm 20:02-0500 # In EST (Eastern U.S. Standard Time).
More generally, the time of the day may be given as
hour:minute:second, where hour is
a number between 0 and 23, minute is a number between 0 and
59, and second is a number between 0 and 59. Alternatively,
:second can be omitted, in which case it is taken to
be zero.
If the time is followed by am or pm (or a.m.
or p.m.), hour is restricted to run from 1 to 12, and
:minute may be omitted (taken to be zero). am
indicates the first half of the day, pm indicates the second
half of the day. In this notation, 12 is the predecessor of 1:
midnight is 12am while noon is 12pm.
The time may alternatively be followed by a time zone correction,
expressed as shhmm, where s is +
or -, hh is a number of zone hours and mm is a number
of zone minutes. When a time zone correction is given this way, it
forces interpretation of the time relative to
Coordinated Universal Time (UTC), overriding any previous
specification for the time zone or the local time zone. The minute
part of the time of the day may not be elided when a time zone correction
is used. This is the only way to specify a time zone correction by
fractional parts of an hour.
Either am/pm or a time zone correction may be specified,
but not both.
A time zone item specifies an international time zone, indicated by
a small set of letters. They are supported for backward compatibility reasons,
but they are not recommended because they are ambiguous in practice:
for example, the abbreviation EST has different meanings in
Australia and the United States. Any included period is ignored. Military
time zone designations use a single letter. Currently, only integral
zone hours may be represented in a time zone item. See the previous
section for a finer control over the time zone correction.
Here are many non-daylight-saving-time time zones, indexed by the zone hour value.
Y for militaries.
X for militaries.
W for militaries.
V for militaries.
PST for Pacific Standard, and
U for militaries.
MST for Mountain Standard, and
T for militaries.
CST for Central Standard, and
S for militaries.
EST for Eastern Standard, and
R for militaries.
AST for Atlantic Standard, and
Q for militaries.
P for militaries.
O for militaries.
N for militaries.
GMT for Greenwich Mean,
UT for Universal,
UTC for Coordinated Universal,
WET for Western European, and
Z for ISO 8601 and militaries.
A for militaries,
CET for Central European,
MET for Midden Europesche Tijd (Dutch), and
MEZ for Mittel-Europäische Zeit (German).
B for militaries, and
EET for Eastern European.
C for militaries.
D for militaries.
E for militaries.
F for militaries.
G for militaries.
H for militaries.
I for militaries, and
JST for Japan Standard.
GST for Guam Standard, and
K for militaries.
L for militaries.
M for militaries, and
NZST for New Zealand Standard.
Here are many daylight-saving time (DST) time zones,
indexed by the zone hour value. Also, by
following a non-DST time zone by the string DST in a separate word
(that is, separated by some whitespace), the corresponding DST time zone
may be specified.
PDT for Pacific Daylight.
MDT for Mountain Daylight.
CDT for Central Daylight.
EDT for Eastern Daylight.
ADT for Atlantic Daylight.
BST for British Summer, and
WEST for Western European Summer.
CEST for Central European Summer,
MEST for Midden Europesche S. Tijd (Dutch), and
MESZ for Mittel-Europäische Sommerzeit (German).
NZDT for New Zealand Daylight.
The explicit mention of a day of the week will forward the date (only if necessary) to reach that day of the week in the future.
Days of the week may be spelled out in full: Sunday,
Monday, Tuesday, Wednesday, Thursday,
Friday or Saturday. Days may be abbreviated to their
first three letters, optionally followed by a period. The special
abbreviations Tues for Tuesday, Wednes for
Wednesday and Thur or Thurs for Thursday are
also allowed.
A number may precede a day of the week item to move forward
supplementary weeks. It is best used in expression like third
monday. In this context, last day or next
day is also acceptable; they move one week before or after
the day that day by itself would represent.
A comma following a day of the week item is ignored.
Relative items adjust a date (or the current date if none) forward or backward. The effects of relative items accumulate. Here are some examples:
1 year 1 year ago 3 years 2 days
The unit of time displacement may be selected by the string year
or month for moving by whole years or months. These are fuzzy
units, as years and months are not all of equal duration. More precise
units are fortnight which is worth 14 days, week worth 7
days, day worth 24 hours, hour worth 60 minutes,
minute or min worth 60 seconds, and second or
sec worth one second. An s suffix on these units is
accepted and ignored.
The unit of time may be preceded by a multiplier, given as an optionally
signed number. Unsigned numbers are taken as positively signed. No
number at all implies 1 for a multiplier. Following a relative item by
the string ago is equivalent to preceding the unit by a
multiplicator with value -1.
The string tomorrow is worth one day in the future (equivalent
to day), the string yesterday is worth
one day in the past (equivalent to day ago).
The strings now or today are relative items corresponding
to zero-valued time displacement, these strings come from the fact
a zero-valued time displacement represents the current time when not
otherwise changed by previous items. They may be used to stress other
items, like in 12:00 today. The string this also has
the meaning of a zero-valued time displacement, but is preferred in
date strings like this thursday.
When a relative item causes the resulting date to cross the boundary between DST and non-DST (or vice-versa), the hour is adjusted according to the local time.
The precise intepretation of a pure decimal number depends on the context in the date string.
If the decimal number is of the form yyyymmdd and no other calendar date item (see Calendar date items) appears before it in the date string, then yyyy is read as the year, mm as the month number and dd as the day of the month, for the specified calendar date.
If the decimal number is of the form hhmm and no other time of day item appears before it in the date string, then hh is read as the hour of the day and mm as the minute of the hour, for the specified time of the day. mm can also be omitted.
If both a calendar date and a time of day appear to the left of a number in the date string, but no relative item, then the number overrides the year.
getdategetdate was originally implemented by Steven M. Bellovin
([email protected]) while at the University of North Carolina
at Chapel Hill. The code was later tweaked by a couple of people on
Usenet, then completely overhauled by Rich $alz ([email protected])
and Jim Berets ([email protected]) in August, 1990. Various
revisions for the GNU system were made by David MacKenzie, Jim Meyering,
Paul Eggert and others.
This chapter was originally produced by François Pinard
([email protected]) from the getdate.y source code,
and then edited by K. Berry ([email protected]).
This section describes commands that display text strings.
echo: Print a line of textecho writes each given string to standard output, with a
space between each and a newline after the last one. Synopsis:
echo [option]... [string]...
The program accepts the following options. Also see Common options.
-n
-e
\a
\b
\c
\f
\n
\r
\t
\v
\\
\nnn
printf: Format and print dataprintf does formatted printing of text. Synopsis:
printf format [argument]...
printf prints the format string, interpreting %
directives and \ escapes in the same way as the C printf
function. The format argument is re-used as necessary to convert
all of the given arguments.
printf has one additional directive, %b, which prints its
argument string with \ escapes interpreted in the same way as in
the format string.
printf interprets \0ooo in format as an octal number
(if ooo is 0 to 3 octal digits) specifying a character to print,
and \xhhh as a hexadecimal number (if hhh is 1 to 3 hex
digits) specifying a character to print.
printf interprets two character syntaxes introduced in ISO C 99:
\u for 16-bit Unicode characters, specified as 4 hex digits
hhhh, and \U for 32-bit Unicode characters, specified as 8 hex
digits hhhhhhhh. printf outputs the Unicode characters
according to the LC_CTYPE part of the current locale, i.e. depending
on the values of the environment variables LC_ALL, LC_CTYPE,
LANG.
The processing of \u and \U requires a full-featured
iconv facility. It is activated on systems with glibc 2.2 (or newer),
or when libiconv is installed prior to the sh-utils. Otherwise the
use of \u and \U will give an error message.
An additional escape, \c, causes printf to produce no
further output.
The only options are a lone --help or
--version. See Common options.
The Unicode character syntaxes are useful for writing strings in a locale independent way. For example, a string containing the Euro currency symbol
$ /usr/local/bin/printf '\u20AC 14.95'
will be output correctly in all locales supporting the Euro symbol (ISO-8859-15, UTF-8, and others). Similarly, a Chinese string
$ /usr/local/bin/printf '\u4e2d\u6587'
will be output correctly in all chinese locales (GB2312, BIG5, UTF-8, etc).
Note that in these examples, the full pathname of printf has been
given, to distinguish it from the GNU bash builtin function
printf.
For larger strings, you don't need to look up the hexadecimal code values of each character one by one. ASCII characters mixed with \u escape sequences is also known as the JAVA source file encoding. You can use GNU recode 3.5c (or newer) to convert strings to this encoding. Here is how to convert a piece of text into a shell script which will output this text in a locale- independent way:
$ LC_CTYPE=zh_CN.big5 /usr/local/bin/printf \
'\u4e2d\u6587\n' > sample.txt
$ recode BIG5..JAVA < sample.txt \
| sed -e "s|^|/usr/local/bin/printf '|" -e "s|$|\\\\n'|" \
> sample.sh
yes: Print a string until interruptedyes prints the command line arguments, separated by spaces and
followed by a newline, forever until it is killed. If no arguments are
given, it prints y followed by a newline forever until killed.
The only options are a lone --help or --version.
See Common options.
This section describes commands that are primarily useful for their exit
status, rather than their output. Thus, they are often used as the
condition of shell if statements, or as the last command in a
pipeline.
false: Do nothing, unsuccessfullyfalse does nothing except return an exit status of 1, meaning
failure. It can be used as a place holder in shell scripts
where an unsuccessful command is needed.
false ignores all command line arguments, even --help
and --version, since to do otherwise would change expected
behavior that some programmers may be relying on.
This version of false is implemented as a C program, and is thus
more secure and faster than a shell script implementation, and may safely
be used as a dummy shell for the purpose of disabling accounts.
true: Do nothing, successfullytrue does nothing except return an exit status of 0, meaning
success. It can be used as a place holder in shell scripts
where a successful command is needed, although the shell built-in
command : (colon) does the same thing faster.
true ignores all command line arguments, even --help
and --version, since to do otherwise would change expected
behavior that some programmers may be relying on.
This version of true is implemented as a C program, and is thus
more secure and faster than a shell script implementation, and may safely
be used as a dummy shell for the purpose of disabling accounts.
test: Check file types and compare valuestest returns a status of 0 (true) or 1 (false) depending on the
evaluation of the conditional expression expr. Each part of the
expression must be a separate argument.
test has file status checks, string operators, and numeric
comparison operators.
Because most shells have a built-in command by the same name, using the unadorned command name in a script or interactively may get you different functionality than that described here.
Besides the options below, test accepts a lone --help or
--version. See Common options. A single non-option argument
is also allowed: test returns true if the argument is not null.
These options test for particular types of files. (Everything's a file, but not all files are the same!)
-b file
-c file
-d file
-f file
-h file
-L file
-p file
-S file
-t [fd]
These options test for particular access permissions.
-g file
-k file
-r file
-u file
-w file
-x file
-O file
-G file
These options test other file characteristics.
-e file
-s file
file1 -nt file2
file1 -ot file2
file1 -ef file2
These options test string characteristics. Strings are not quoted for
test, though you may need to quote them to protect characters
with special meaning to the shell, e.g., spaces.
-z string
-n string
string
string1 = string2
string1 != string2
Numeric relationals. The arguments must be entirely numeric (possibly
negative), or the special expression -l string, which
evaluates to the length of string.
arg1 -eq arg2
arg1 -ne arg2
arg1 -lt arg2
arg1 -le arg2
arg1 -gt arg2
arg1 -ge arg2
For example:
test -1 -gt -2 && echo yes => yes test -l abc -gt 1 && echo yes => yes test 0x100 -eq 1 error--> test: integer expression expected before -eq
testThe usual logical connectives.
! expr
expr1 -a expr2
expr1 -o expr2
expr: Evaluate expressionsexpr evaluates an expression and writes the result on standard
output. Each token of the expression must be a separate argument.
Operands are either numbers or strings. expr converts
anything appearing in an operand position to an integer or a string
depending on the operation being applied to it.
Strings are not quoted for expr itself, though you may need to
quote them to protect characters with special meaning to the shell,
e.g., spaces.
Operators may given as infix symbols or prefix keywords. Parentheses may be used for grouping in the usual manner (you must quote parentheses to avoid the shell evaluating them, however).
Exit status:
0 if the expression is neither null nor 0, 1 if the expression is null or 0, 2 for invalid expressions.
expr supports pattern matching and other string operators. These
have lower precedence than both the numeric and relational operators (in
the next sections).
string : regex
grep) regular
expression, with a ^ implicitly prepended. The first argument is
then matched against this regular expression.
If the match succeeds and regex uses \( and \), the
: expression returns the part of string that matched the
subexpression; otherwise, it returns the number of characters matched.
If the match fails, the : operator returns the null string if
\( and \) are used in regex, otherwise 0.
Only the first \( ... \) pair is relevant to the return
value; additional pairs are meaningful only for grouping the regular
expression operators.
In the regular expression, \+, \?, and \| are
operators which respectively match one or more, zero or one, or separate
alternatives. SunOS and other expr's treat these as regular
characters. (POSIX allows either behavior.)
See Top, for details of
regular expression syntax. Some examples are in Examples of expr.
match string regex
string : regex.
substr string position length
index string charset
length string
quote token
/.
This makes it possible to test expr length quote "$x" or
expr quote "$x" : '.*/\(.\)' and have it do the right thing even if
the value of $x happens to be (for example) / or index.
This operator is a GNU extension. It is disabled when
the environment variable POSIXLY_CORRECT is set.
To make expr interpret keywords as strings, you must use the
quote operator.
expr supports the usual numeric operators, in order of increasing
precedence. The string operators (previous section) have lower precedence,
the connectives (next section) have higher.
+ -
* / %
exprexpr supports the usual logical connectives and relations. These
are higher precedence than either the string or numeric operators
(previous sections). Here is the list, lowest-precedence operator first.
|
&
< <= = == != >= >
== is a synonym for =. expr first tries to convert
both arguments to numbers and do a numeric comparison; if either
conversion fails, it does a lexicographic comparison.
exprHere are a few examples, including quoting for shell metacharacters.
To add 1 to the shell variable foo, in Bourne-compatible shells:
foo=`expr $foo + 1`
To print the non-directory part of the file name stored in
$fname, which need not contain a /.
expr $fname : '.*/\(^.*\)' '^|' $fname
An example showing that \+ is an operator:
expr aaa : 'a\+' => 3
expr abc : 'a\(.\)c' => b expr index abcdef cz => 3 expr index index a error--> expr: syntax error expr index quote index a => 0
Unix shells commonly provide several forms of redirection--ways to change the input source or output destination of a command. But one useful redirection is performed by a separate command, not by the shell; it's described here.
tee: Redirect output to multiple filesThe tee command copies standard input to standard output and also
to any files given as arguments. This is useful when you want not only
to send some data down a pipe, but also to save a copy. Synopsis:
tee [option]... [file]...
If a file being written to does not already exist, it is created. If a
file being written to already exists, the data it previously contained
is overwritten unless the -a option is used.
The program accepts the following options. Also see Common options.
-a
--append
-i
--ignore-interrupts
This section describes commands that manipulate file names.
basename: Strip directory and suffix from a file namebasename removes any leading directory components from
name. Synopsis:
basename name [suffix]
If suffix is specified and is identical to the end of name,
it is removed from name as well. basename prints the
result on standard output.
The only options are --help and --version. See Common options.
dirname: Strip non-directory suffix from a file namedirname prints all but the final slash-delimited component of
a string (presumably a filename). Synopsis:
dirname name
If name is a single component, dirname prints .
(meaning the current directory).
The only options are --help and --version. See Common options.
pathchk: Check file name portabilitypathchk checks portability of filenames. Synopsis:
pathchk [option]... name...
For each name, pathchk prints a message if any of
these conditions is true:
The program accepts the following option. Also see Common options.
-p
--portability
Exit status:
0 if all specified file names passed all of the tests, 1 otherwise.
This section describes commands that display or alter the context in which you are working: the current directory, the terminal settings, and so forth. See also the user-related commands in the next section.
pwd: Print working directorypwd prints the fully resolved name of the current directory.
That is, all components of the printed name will be actual directory
names--none will be symbolic links.
Because most shells have a built-in command by the same name, using the unadorned command name in a script or interactively may get you different functionality than that described here.
The only options are a lone --help or
--version. See Common options.
stty: Print or change terminal characteristicsstty prints or changes terminal characteristics, such as baud rate.
Synopses:
stty [option] [setting]... stty [option]
If given no line settings, stty prints the baud rate, line
discipline number (on systems that support it), and line settings
that have been changed from the values set by stty sane.
By default, mode reading and setting are performed on the tty line
connected to standard input, although this can be modified by the
--file option.
stty accepts many non-option arguments that change aspects of
the terminal line operation, as described below.
The program accepts the following options. Also see Common options.
-a
--all
-F device
--file=device
O_NONDELAY flag to
prevent a POSIX tty from blocking until the carrier detect line is high if
the clocal flag is not set. Hence, it is not always possible
to allow the shell to open the device in the traditional manner.
-g
--save
stty command to restore the current settings. This option
may not be used in combination with any line settings.
Many settings can be turned off by preceding them with a -.
Such arguments are marked below with "May be negated" in their
description. The descriptions themselves refer to the positive
case, that is, when not negated (unless stated otherwise,
of course).
Some settings are not available on all POSIX systems, since they use extensions. Such arguments are marked below with "Non-POSIX" in their description. On non-POSIX systems, those or other settings also may not be available, but it's not feasible to document all the variations: just try it and see.
Control settings:
parenb
parodd
cs5
cs6
cs7
cs8
hup
hupcl
cstopb
cread
clocal
crtscts
ignbrk
brkint
ignpar
parmrk
inpck
istrip
inlcr
igncr
icrnl
ixon
ixoff
tandem
stop character when the system input buffer
is almost full, and start character when it becomes almost
empty again. May be negated.
iuclc
ixany
imaxbel
These arguments specify output-related operations.
opost
olcuc
ocrnl
onlcr
onocr
onlret
ofill
ofdel
nl1
nl0
cr3
cr2
cr1
cr0
tab3
tab2
tab1
tab0
bs1
bs0
vt1
vt0
ff1
ff0
isig
interrupt, quit, and suspend special
characters. May be negated.
icanon
erase, kill, werase, and rprnt
special characters. May be negated.
iexten
echo
echoe
crterase
erase characters as backspace-space-backspace. May be
negated.
echok
kill character. May be negated.
echonl
noflsh
interrupt and quit special
characters. May be negated.
xcase
\, when icanon is set.
Non-POSIX. May be negated.
tostop
echoprt
prterase
\ and /.
Non-POSIX. May be negated.
echoctl
ctlecho
^c) instead
of literally. Non-POSIX. May be negated.
echoke
crtkill
kill special character by erasing each character on
the line as indicated by the echoprt and echoe settings,
instead of by the echoctl and echok settings. Non-POSIX.
May be negated.
Combination settings:
evenp
parity
parenb -parodd cs7. May be negated. If negated, same
as -parenb cs8.
oddp
parenb parodd cs7. May be negated. If negated, same
as -parenb cs8.
nl
-icrnl -onlcr. May be negated. If negated, same as
icrnl -inlcr -igncr onlcr -ocrnl -onlret.
ek
erase and kill special characters to their default
values.
sane
cread -ignbrk brkint -inlcr -igncr icrnl -ixoff -iuclc -ixany imaxbel opost -olcuc -ocrnl onlcr -onocr -onlret -ofill -ofdel nl0 cr0 tab0 bs0 vt0 ff0 isig icanon iexten echo echoe echok -echonl -noflsh -xcase -tostop -echoprt echoctl echokeand also sets all special characters to their default values.
cooked
brkint ignpar istrip icrnl ixon opost isig icanon, plus
sets the eof and eol characters to their default values
if they are the same as the min and time characters.
May be negated. If negated, same as raw.
raw
-ignbrk -brkint -ignpar -parmrk -inpck -istrip -inlcr -igncr -icrnl -ixon -ixoff -iuclc -ixany -imaxbel -opost -isig -icanon -xcase min 1 time 0May be negated. If negated, same as
cooked.
cbreak
-icanon. May be negated. If negated, same as
icanon.
pass8
-parenb -istrip cs8. May be negated. If negated,
same as parenb istrip cs7.
litout
-parenb -istrip -opost cs8. May be negated.
If negated, same as parenb istrip opost cs7.
decctlq
-ixany. Non-POSIX. May be negated.
tabs
tab0. Non-POSIX. May be negated. If negated, same
as tab3.
lcase
LCASE
xcase iuclc olcuc. Non-POSIX. May be negated.
crt
echoe echoctl echoke.
dec
echoe echoctl echoke -ixany intr ^C erase ^? kill C-u.
The special characters' default values vary from system to system.
They are set with the syntax name value, where the names are
listed below and the value can be given either literally, in hat
notation (^c), or as an integer which may start with
0x to indicate hexadecimal, 0 to indicate octal, or
any other digit to indicate decimal.
For GNU stty, giving a value of ^- or undef disables that
special character. (This is incompatible with Ultrix stty,
which uses a value of u to disable a special character. GNU
stty treats a value u like any other, namely to set that
special character to <U>.)
intr
quit
erase
kill
eof
eol
eol2
swtch
start
stop
susp
dsusp
rprnt
werase
lnext
min n
-icanon is set.
time n
-icanon is set.
ispeed n
ospeed n
rows n
cols n
columns n
size
LINES and COLUMNS
instead; however, GNU stty does not know anything about them.)
Non-POSIX.
line n
speed
n
exta extb. exta is the same as
19200; extb is the same as 38400. 0 hangs up the line if
-clocal is set.
printenv: Print all or some environment variablesprintenv prints environment variable values. Synopsis:
printenv [option] [variable]...
If no variables are specified, printenv prints the value of
every environment variable. Otherwise, it prints the value of each
variable that is set, and nothing for those that are not set.
The only options are a lone --help or --version.
See Common options.
Exit status:
0 if all variables specified were found 1 if at least one specified variable was not found 2 if a write error occurred
tty: Print file name of terminal on standard inputtty prints the file name of the terminal connected to its standard
input. It prints not a tty if standard input is not a terminal.
Synopsis:
tty [option]...
The program accepts the following option. Also see Common options.
-s
--silent
--quiet
Exit status:
0 if standard input is a terminal 1 if standard input is not a terminal 2 if given incorrect arguments 3 if a write error occurs
This section describes commands that print user-related information: logins, groups, and so forth.
id: Print real and effective uid and gidid prints information about the given user, or the process
running it if no user is specified. Synopsis:
id [option]... [username]
By default, it prints the real user id, real group id, effective user id if different from the real user id, effective group id if different from the real group id, and supplemental group ids.
Each of these numeric values is preceded by an identifying string and followed by the corresponding user or group name in parentheses.
The options cause id to print only part of the above information.
Also see Common options.
-g
--group
-G
--groups
-n
--name
-u, -g, or -G.
-r
--real
-u, -g, or -G.
-u
--user
logname: Print current login namelogname prints the calling user's name, as found in the file
/etc/utmp, and exits with a status of 0. If there is no
/etc/utmp entry for the calling process, logname prints
an error message and exits with a status of 1.
The only options are --help and --version. See Common options.
whoami: Print effective user idwhoami prints the user name associated with the current
effective user id. It is equivalent to the command id -un.
The only options are --help and --version. See Common options.
groups: Print group names a user is ingroups prints the names of the primary and any supplementary
groups for each given username, or the current process if no names
are given. If names are given, the name of each user is printed before
the list of that user's groups. Synopsis:
groups [username]...
The group lists are equivalent to the output of the command id -Gn.
The only options are --help and --version. See Common options.
users: Print login names of users currently logged inusers prints on a single line a blank-separated list of user
names of users currently logged in to the current host. Each user name
corresponds to a login session, so if a user has more than one login
session, that user's name will appear the same number of times in the
output. Synopsis:
users [file]
With no file argument, users extracts its information from
the file /etc/utmp. If a file argument is given, users
uses that file instead. A common choice is /etc/wtmp.
The only options are --help and --version. See Common options.
who: Print who is currently logged inwho prints information about users who are currently logged on.
Synopsis:
who [option] [file] [am i]
If given no non-option arguments, who prints the following
information for each user currently logged on: login name, terminal
line, login time, and remote hostname or X display.
If given one non-option argument, who uses that instead of
/etc/utmp as the name of the file containing the record of
users logged on. /etc/wtmp is commonly given as an argument
to who to look at who has previously logged on.
If given two non-option arguments, who prints only the entry
for the user running it (determined from its standard input), preceded
by the hostname. Traditionally, the two arguments given are am
i, as in who am i.
The program accepts the following options. Also see Common options.
-m
who am i.
-q
--count
-s
who.
-i
-u
--idle
. means the user was active in last minute.
old means the user was idle for more than 24 hours.
-l
--lookup
-H
--heading
-w
-T
--mesg
--message
--writable
+allowingwritemessages-disallowingwritemessages?cannot find terminal device
This section describes commands that print or change system-wide information.
date: Print or set system date and timedate with no arguments prints the current time and date, in the
format of the %c directive (described below). Synopses:
date [option]... [+format] date [-u|--utc|--universal] [ MMDDhhmm[[CC]YY][.ss] ]
If given an argument that starts with a +, date prints the
current time and date (or the time and date specified by the
--date option, see below) in the format defined by that argument,
which is the same as in the strftime function. Except for
directives, which start with %, characters in the format string
are printed unchanged. The directives are described below.
date directives related to times.
%H
%I
%k
%l
%M
%p
%r
%s
--date option.
%S
%T
%X
%z
--date option.
%Z
--date option.
date directives related to dates.
%a
%A
%b
%B
%c
%d
%D
%h
%j
%m
%U
%V
%w
%W
%x
%y
%Y
date directives that produce literal strings.
%%
%n
%t
By default, date pads numeric fields with zeroes, so that, for
example, numeric months are always output as two digits. GNU date
recognizes the following numeric modifiers between the % and the
directive.
-
_
These are GNU extensions.
Here is an example illustrating the differences:
date +%d/%m -d "Feb 1" => 01/02 date +%-d/%-m -d "Feb 1" => 1/2 date +%_d/%_m -d "Feb 1" => 1/ 2
If given an argument that does not start with +, date sets
the system clock to the time and date specified by that argument (as
described below). You must have appropriate privileges to set the
system clock. The --date and --set options may not be
used with such an argument. The --universal option may be used
with such an argument to indicate that the specified time and date are
relative to Coordinated Universal Time rather than to the local time
zone.
The argument must consist entirely of digits, which have the following meaning:
MM
DD
hh
mm
CC
YY
ss
The --set option also sets the system clock; see the next section.
dateThe program accepts the following options. Also see Common options.
-d datestr
--date=datestr
am and pm,
yesterday, ago, next, etc. See Date input formats.
-f datefile
--file=datefile
-d and display the
resulting time and date. If datefile is -, use standard
input. This is useful when you have many dates to process, because the
system overhead of starting up the date executable many times can
be considerable.
-I[timespec]
--iso-8601[=timespec]
%Y-%m-%d.
The optional argument timespec specifies the number of additional terms of the time to include. It can be one of the following:
auto
hours
minutes
seconds
If showing any time terms, then include the time zone using the format
%z.
-R
--rfc-822
%a, %_d %b %Y %H:%M:%S %z.
-r file
--reference=file
-s datestr
--set=datestr
-d above.
-u
--utc
--universal
TZ environment variable was set to the string UTC0.
Normally, date operates in the time zone indicated by
TZ, or the system default if TZ is not set. Coordinated
Universal Time is often called "Greenwich Mean Time" (GMT) for
historical reasons.
dateHere are a few examples. Also see the documentation for the -d
option in the previous section.
date --date='2 days ago'
date --date='3 months 1 day'
date --date='25 Dec' +%j
date '+%B %d'
But this may not be what you want because for the first nine days of
the month, the %d expands to a zero-padded two-digit field,
for example date -d 1may '+%B %d' will print May 01.
- modifier to suppress
the padding altogether.
date -d=1may '+%B %-d'
date when setting the system clock:
date +%m%d%H%M%Y.%S
date --set='+2 minutes'
date --rfc. I just did and saw this:
Mon, 25 Mar 1996 23:34:17 -0600
--date option with
the %s format. That can be useful in sorting and/or graphing
and/or comparing data by date. The following command outputs the
number of the seconds since the epoch for the time one second later
than the epoch, but in a time zone five hours later (Cambridge, Massachusetts),
thus a total of five hours and one second after the epoch:
date --date='1970-01-01 00:00:01 UTC +5 hours' +%s 18001
Suppose you had not specified time zone information in the example above.
Then, date would have used your computer's idea of the time zone when
interpreting the string. Here's what you would get if you were in
Greenwich, England:
# local time zone used date --date='1970-01-01 00:00:01' +%s 1
946684800 and casually note "Oh, that's the first second
of the year 2000."
date --date='2000-01-01 UTC' +%s 946684800
To convert such an unwieldy number of seconds back to a more readable form, use a command like this:
date -d '1970-01-01 946684800 sec' +"%Y-%m-%d %T %z" 2000-01-01 00:00:00 +0000
uname: Print system informationuname prints information about the machine and operating system
it is run on. If no options are given, uname acts as if the
-s option were given. Synopsis:
uname [option]...
If multiple options or -a are given, the selected information is
printed in this order:
sysname nodename release osversion machine
The osversion, at least, may well be multiple words. For example:
uname -a => Linux hayley 1.0.4 #3 Thu May 12 18:06:34 1994 i486
The program accepts the following options. Also see Common options.
-a
--all
-m
--machine
-n
--nodename
-p
--processor
-r
--release
-s
--sysname
-v
hostname: Print or set system nameWith no arguments, hostname prints the name of the current host
system. With one argument, it sets the current host name to the
specified string. You must have appropriate privileges to set the host
name. Synopsis:
hostname [name]
The only options are --help and --version. See Common options.
hostid: Print numeric host identifier.hostid prints the numeric identifier of the current host
in hexadecimal. This command accepts no arguments.
The only options are --help and --version.
See Common options.
For example, here's what it prints on one system I use:
$ hostid 1bac013d
On that system, the 32-bit quantity happens to be closely related to the system's Internet address, but that isn't always the case.
This section describes commands that run other commands in some context different than the current one: a modified environment, as a different user, etc.
chroot: Run a command with a different root directorychroot runs a command with a specified root directory.
On many systems, only the super-user can do this.
Synopses:
chroot newroot [command [args]...] chroot option
Ordinarily, filenames are looked up starting at the root of the
directory structure, i.e., /. chroot changes the root to
the directory newroot (which must exist) and then runs
command with optional args. If command is not
specified, the default is the value of the SHELL environment
variable or /bin/sh if not set, invoked with the -i option.
The only options are --help and --version. See Common options.
Here are a few tips to help avoid common problems in using chroot. To start with a simple example, make command refer to a statically linked binary. If you were to use a dynamically linked executable, then you'd have to arrange to have the shared libraries in the right place under your new root directory.
For example, if you create a statically linked `ls' executable, and put it in /tmp/empty, you can run this command as root:
$ chroot /tmp/empty /ls -Rl /
Then you'll see output like this:
/: total 1023 -rwxr-xr-x 1 0 0 1041745 Aug 16 11:17 ls
If you want to use a dynamically linked executable, say bash,
then first run ldd bash to see what shared objects it needs.
Then, in addition to copying the actual binary, also copy the listed
files to the required positions under your intended new root directory.
Finally, if the executable requires any other files (e.g., data, state,
device files), copy them into place, too.
env: Run a command in a modified environmentenv runs a command with a modified environment. Synopses:
env [option]... [name=value]... [command [args]...] env
Arguments of the form variable=value set
the environment variable variable to value value.
value may be empty (variable=). Setting a variable
to an empty value is different from unsetting it.
The first remaining argument specifies the program name to invoke; it is
searched for according to the PATH environment variable. Any
remaining arguments are passed as arguments to that program.
If no command name is specified following the environment
specifications, the resulting environment is printed. This is like
specifying a command name of printenv.
The program accepts the following options. Also see Common options.
-u name
--unset=name
-
-i
--ignore-environment
nice: Run a command with modified scheduling prioritynice prints or modifies the scheduling priority of a job.
Synopsis:
nice [option]... [command [arg]...]
If no arguments are given, nice prints the current scheduling
priority, which it inherited. Otherwise, nice runs the given
command with its scheduling priority adjusted. If no
adjustment is given, the priority of the command is incremented by
10. You must have appropriate privileges to specify a negative
adjustment. The priority can be adjusted by nice over the range
of -20 (the highest priority) to 19 (the lowest).
Because most shells have a built-in command by the same name, using the unadorned command name in a script or interactively may get you different functionality than that described here.
The program accepts the following option. Also see Common options.
-n adjustment
-adjustment
--adjustment=adjustment
nohup: Run a command immune to hangupsnohup runs the given command with hangup signals ignored,
so that the command can continue running in the background after you log
out. Synopsis:
nohup command [arg]...
nohup increases the scheduling priority of command by 5, so
it has a slightly smaller change to run. If standard output is a terminal,
it and standard error are redirected so that they are appended to the
file nohup.out; if that cannot be written to, they are appended
to the file $HOME/nohup.out. If that cannot be written to, the
command is not run.
If nohup creates either nohup.out or
$HOME/nohup.out, it creates it with no "group" or "other"
access permissions. It does not change the permissions if the output
file already existed.
nohup does not automatically put the command it runs in the
background; you must do that explicitly, by ending the command line
with an &.
The only options are --help and --version. See Common options.
su: Run a command with substitute user and group idsu allows one user to temporarily become another user. It runs a
command (often an interactive shell) with the real and effective user
id, group id, and supplemental groups of a given user. Synopsis:
su [option]... [user [arg]...]
If no user is given, the default is root, the super-user.
The shell to use is taken from user's passwd entry, or
/bin/sh if none is specified there. If user has a
password, su prompts for the password unless run by a user with
effective user id of zero (the super-user).
By default, su does not change the current directory.
It sets the environment variables HOME and SHELL
from the password entry for user, and if user is not
the super-user, sets USER and LOGNAME to user.
By default, the shell is not a login shell.
Any additional args are passed as additional arguments to the shell.
GNU su does not treat /bin/sh or any other shells specially
(e.g., by setting argv[0] to -su, passing -c only
to certain shells, etc.).
su can optionally be compiled to use syslog to report
failed, and optionally successful, su attempts. (If the system
supports syslog.) However, GNU su does not check if the
user is a member of the wheel group; see below.
The program accepts the following options. Also see Common options.
-c command
--command=command
-c option instead of starting an interactive shell.
-f
--fast
-f option to the shell. This probably only makes sense
if the shell run is csh or tcsh, for which the -f
option prevents reading the startup file (.cshrc). With
Bourne-like shells, the -f option disables file name pattern
expansion (globbing), which is not likely to be useful.
-
-l
--login
TERM, HOME, and SHELL
(which are set as described above), and USER and LOGNAME
(which are set, even for the super-user, as described above), and set
PATH to a compiled-in default value. Change to user's home
directory. Prepend - to the shell's name, intended to make it
read its login startup file(s).
-m
-p
--preserve-environment
HOME, USER,
LOGNAME, or SHELL. Run the shell given in the environment
variable SHELL instead of the shell from user's passwd
entry, unless the user running su is not the superuser and
user's shell is restricted. A restricted shell is one that
is not listed in the file /etc/shells, or in a compiled-in list
if that file does not exist. Parts of what this option does can be
overridden by --login and --shell.
-s shell
--shell=shell
su is not the superuser and user's
shell is restricted (see -m just above).
su does not support the wheel group(This section is by Richard Stallman.)
Sometimes a few of the users try to hold total power over all the rest. For example, in 1984, a few users at the MIT AI lab decided to seize power by changing the operator password on the Twenex system and keeping it secret from everyone else. (I was able to thwart this coup and give power back to the users by patching the kernel, but I wouldn't know how to do that in Unix.)
However, occasionally the rulers do tell someone. Under the usual
su mechanism, once someone learns the root password who
sympathizes with the ordinary users, he or she can tell the rest. The
"wheel group" feature would make this impossible, and thus cement the
power of the rulers.
I'm on the side of the masses, not that of the rulers. If you are used to supporting the bosses and sysadmins in whatever they do, you might find this idea strange at first.
sleep: Delay for a specified timesleep pauses for an amount of time specified by the sum of
the values of the command line arguments.
Synopsis:
sleep number[smhd]...
Each argument is a number followed by an optional unit; the default is seconds. The units are:
s
m
h
d
Historical implementations of sleep have required that
number be an integer. However, GNU sleep accepts
arbitrary floating point numbers.
The only options are --help and --version. See Common options.
These programs do numerically-related operations.
factor: Print prime factorsfactor prints prime factors. Synopses:
factor [number]... factor option
If no number is specified on the command line, factor reads
numbers from standard input, delimited by newlines, tabs, or spaces.
The only options are --help and --version. See Common options.
The algorithm it uses is not very sophisticated, so for some inputs
factor runs for a long time. The hardest numbers to factor are
the products of large primes. Factoring the product of the two largest 32-bit
prime numbers takes over 10 minutes of CPU time on a 400MHz Pentium II.
$ p=`echo '4294967279 * 4294967291'|bc` $ factor $p 18446743979220271189: 4294967279 4294967291
In contrast, factor factors the largest 64-bit number in just
over a tenth of a second:
$ factor `echo '2^64-1'|bc` 18446744073709551615: 3 5 17 257 641 65537 6700417
seq: Print numeric sequencesseq prints a sequence of numbers to standard output. Synopses:
seq [option]... [first [increment]] last...
seq prints the numbers from first to last by
increment. By default, first and increment are both 1,
and each number is printed on its own line. All numbers can be reals,
not just integers.
The program accepts the following options. Also see Common options.
-f format
--format=format
%g.
format must contain exactly one of the floating point
output formats %e, %f, or %g.
-s string
--separator=string
-w
--equal-width
--format).
If you want to use seq to print sequences of large integer values,
don't use the default %g format since it can result in
loss of precision:
$ seq 1000000 1000001 1e+06 1e+06
Instead, you can use the format, %1.f,
to print large decimal numbers with no exponent and no decimal point.
$ seq --format=%1.f 1000000 1000001 1000000 1000001
If you want hexadecimal output, you can use printf
to perform the conversion:
$ printf %x'\n' `seq -f %1.f 1048575 1024 1050623` fffff 1003ff 1007ff
For very long lists of numbers, use xargs to avoid system limitations on the length of an argument list:
$ seq -f %1.f 1000000 | xargs printf %x'\n' |tail -3 f423e f423f f4240
To generate octal output, use the printf %o format instead
of %x. Note however that using printf works only for numbers
smaller than 2^32:
$ printf "%x\n" `seq -f %1.f 4294967295 4294967296` ffffffff bash: printf: 4294967296: Numerical result out of range
On most systems, seq can produce whole-number output for values up to
2^53, so here's a more general approach to base conversion that
also happens to be more robust for such large numbers. It works by
using bc and setting its output radix variable, obase,
to 16 in this case to produce hexadecimal output.
$ (echo obase=16; seq -f %1.f 4294967295 4294967296)|bc FFFFFFFF 100000000
Be careful when using seq with a fractional increment,
otherwise you may see surprising results. Most people would expect to
see 0.3 printed as the last number in this example:
$ seq -s' ' 0 .1 .3 0 0.1 0.2
But doesn't happen on most systems because seq is implemented using
binary floating point arithmetic (via the C double type) - which
means some decimal numbers like .1 cannot be represented exactly.
That in turn means some nonintuitive conditions like .1 * 3 > .3
will end up being true.
To work around that in the above example, use a slightly larger number as the last value:
$ seq -s' ' 0 .1 .31 0 0.1 0.2 0.3
In general, when using an increment with a fractional part, where (last - first) / increment is (mathematically) a whole number, specify a slightly larger (or smaller, if increment is negative) value for last to ensure that last is the final value printed by seq.
!: Connectives for test
!=: String tests
%: Numeric expressions
&: Relations for expr
*: Numeric expressions
+: Numeric expressions
-: Numeric expressions, env invocation, su invocation
--adjustment: nice invocation
--all: uname invocation, stty invocation
--append: tee invocation
--command: su invocation
--count: who invocation
--date: Options for date
--fast: su invocation
--file: stty invocation, Options for date
--format=format: seq invocation
--group: id invocation
--groups: id invocation
--heading: who invocation
--help: Common options
--idle: who invocation
--ignore-environment: env invocation
--ignore-interrupts: tee invocation
--iso-8601[=timespec]: Options for date
--login: su invocation
--lookup: who invocation
--machine: uname invocation
--mesg: who invocation
--message: who invocation
--name: id invocation
--nodename: uname invocation
--portability: pathchk invocation
--preserve-environment: su invocation
--processor: uname invocation
--quiet: tty invocation
--real: id invocation
--reference: Options for date
--release: uname invocation
--rfc-822: Options for date
--save: stty invocation
--set: Options for date
--shell: su invocation
--silent: tty invocation
--sysname: uname invocation
--universal: Options for date
--user: id invocation
--utc: Options for date
--version: Common options
--writable: who invocation
-a: stty invocation, uname invocation, tee invocation, Connectives for test
-adjustment: nice invocation
-b: File type tests
-c: su invocation, File type tests
-d: Options for date, File type tests
-e: File characteristics tests, echo invocation
-ef: File characteristics tests
-eq: Numeric tests
-F: stty invocation
-f: su invocation, Options for date, File type tests
-f format: seq invocation
-g: stty invocation
-G: id invocation
-g: Access permission tests
-G: Access permission tests
-g: id invocation
-ge: Numeric tests
-gt: Numeric tests
-H: who invocation
-h: File type tests
-i: who invocation, tee invocation, env invocation
-I[timespec]: Options for date
-k: Access permission tests
-L: File type tests
-l: su invocation, who invocation
-le: Numeric tests
-lt: Numeric tests
-m: who invocation, uname invocation, su invocation
-n: String tests, uname invocation, nice invocation, echo invocation, id invocation
-ne: Numeric tests
-nt: File characteristics tests
-o: Connectives for test
-O: Access permission tests
-ot: File characteristics tests
-p: uname invocation, su invocation, pathchk invocation, File type tests
-q: who invocation
-R: Options for date
-r: id invocation, uname invocation, Access permission tests, Options for date
-s: su invocation, Options for date, tty invocation, File characteristics tests, uname invocation
-S: File type tests
-s: who invocation
-su: su invocation
-T: who invocation
-t: File type tests
-u: Access permission tests, id invocation, env invocation, who invocation, Options for date
-unset: env invocation
-v: uname invocation
-w: Access permission tests, who invocation
-x: Access permission tests
-z: String tests
.cshrc: su invocation
/: Numeric expressions
/bin/sh: su invocation
/etc/passwd: su invocation
/etc/shells: su invocation
/etc/utmp: logname invocation, who invocation, users invocation
/etc/wtmp: users invocation, who invocation
<: Relations for expr
<=: Relations for expr
=: String tests, Relations for expr
==: Relations for expr
>: Relations for expr
>=: Relations for expr
\( regexp operator\+ regexp operator\0ooo: printf invocation
\0xhhh: printf invocation
\? regexp operator\c: printf invocation
\uhhhh: printf invocation
\Uhhhhhhhh: printf invocation
\| regexp operatorago in date stringsam i: who invocation
am in date stringsgetdate: Authors of getdate
basename: basename invocation
brkint: Input
bsn: Output
C-s/C-q flow control: Input
cbreak: Combination
chroot: chroot invocation
clocal: Control
cols: Special
COLUMNS: Special
columns: Special
^c: Local
cooked: Combination
cread: Control
crn: Output
crt: Combination
crterase: Local
crtkill: Local
crtscts: Control
csn: Control
cstopb: Control
ctlecho: Local
date: date invocation
date options: Options for date
day in date stringsdec: Combination
decctlq: Combination
dirname: dirname invocation
dsusp: Characters
echo: echo invocation, Local
echoctl: Local
echoe: Local
echok: Local
echoke: Local
echonl: Local
echoprt: Local
ek: Combination
env: env invocation
eof: Characters
eol: Characters
eol2: Characters
erase: Characters
evenp: Combination
date: Examples of date
expr: Examples of expr
expr: expr invocation
false: false invocation
pathchk: pathchk invocation
printenv: printenv invocation
true: true invocation
tty: tty invocation
expr: expr invocation
factor: factor invocation
false: false invocation
ffn: Output
first in date stringsseq: seq invocation
fortnight in date stringsgetdate: Date input formats
groups: groups invocation
HOME: su invocation
hostid: hostid invocation
hour in date stringshup[cl]: Control
icanon: Local
icrnl: Input
id: id invocation
iexten: Local
ignbrk: Input
igncr: Input
ignpar: Input
imaxbel: Input
index: String expressions
inlcr: Input
inpck: Input
intr: Characters
isig: Local
ispeed: Special
istrip: Input
iuclc: Input
ixany: Input
ixoff: Input
ixon: Input
kill: Characters
last day: Day of week items, Options for date
last in date stringslcase: Combination
LCASE: Combination
length: String expressions
line: Special
LINES: Special
litout: Combination
lnext: Characters
LOGNAME: su invocation
logname: logname invocation
stty output: stty invocation
match: String expressions
midnight in date stringsmin: Special
minute in date stringsmonth in date stringskill: Local
next day: Day of week items, Options for date
next in date stringsnice: nice invocation
nl: Combination
nln: Output
noflsh: Local
nohup: nohup invocation
nohup.out: nohup invocation
noon in date stringsnow in date stringsocrnl: Output
oddp: Combination
ofdel: Output
ofill: Output
olcuc: Output
onlcr: Output
onlret: Output
onocr: Output
opost: Output
date: Options for date
ospeed: Special
parenb: Control
parity: Combination
parmrk: Input
parodd: Control
pass8: Combination
su shell: su invocation
PATH: env invocation, su invocation
pathchk: pathchk invocation
pm in date stringsprintenv: printenv invocation
printf: printf invocation
prterase: Local
pwd: pwd invocation
quit: Characters
quote: String expressions
raw: Combination
rows: Special
rprnt: Characters
sane: Combination
seq: seq invocation
seq: seq invocation
SHELL: su invocation
size: Special
sleep: sleep invocation
speed: Special
start: Characters
stop: Characters
strftime and datestty: stty invocation
su: su invocation
substr: String expressions
susp: Characters
swtch: Characters
pwd: pwd invocation
syslog: su invocation
tabn: Output
tabs: Combination
tandem: Input
tee: tee invocation
TERM: su invocation
test: test invocation
this in date stringstime: Special
today in date stringstomorrow: Options for date
tomorrow in date stringstostop: Local
true: true invocation
tty: tty invocation
u, and disabling special charactersuname: uname invocation
USER: su invocation
users: users invocation
utmp: logname invocation
vtn: Output
week in date stringswerase: Characters
who: who invocation
who am i: who invocation
whoami: whoami invocation
write, allowedxcase: Local
year in date stringsyes: yes invocation
yesterday: Options for date
yesterday in date strings|: Relations for expr