mirror of
https://git.hardenedbsd.org/hardenedbsd/HardenedBSD.git
synced 2024-12-23 10:06:25 +01:00
be848c7a13
MFC after: 2 weeks
416 lines
11 KiB
Groff
416 lines
11 KiB
Groff
.\" $FreeBSD$
|
|
.\" $OpenBSD: bc.1,v 1.30 2014/01/14 07:42:42 jmc Exp $
|
|
.\"
|
|
.\" Copyright (C) Caldera International Inc. 2001-2002.
|
|
.\" All rights reserved.
|
|
.\"
|
|
.\" Redistribution and use in source and binary forms, with or without
|
|
.\" modification, are permitted provided that the following conditions
|
|
.\" are met:
|
|
.\" 1. Redistributions of source code and documentation must retain the above
|
|
.\" copyright notice, this list of conditions and the following disclaimer.
|
|
.\" 2. Redistributions in binary form must reproduce the above copyright
|
|
.\" notice, this list of conditions and the following disclaimer in the
|
|
.\" documentation and/or other materials provided with the distribution.
|
|
.\" 3. All advertising materials mentioning features or use of this software
|
|
.\" must display the following acknowledgement:
|
|
.\" This product includes software developed or owned by Caldera
|
|
.\" International, Inc.
|
|
.\" 4. Neither the name of Caldera International, Inc. nor the names of other
|
|
.\" contributors may be used to endorse or promote products derived from
|
|
.\" this software without specific prior written permission.
|
|
.\"
|
|
.\" USE OF THE SOFTWARE PROVIDED FOR UNDER THIS LICENSE BY CALDERA
|
|
.\" INTERNATIONAL, INC. AND CONTRIBUTORS ``AS IS'' AND ANY EXPRESS OR
|
|
.\" IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
|
|
.\" OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
|
|
.\" IN NO EVENT SHALL CALDERA INTERNATIONAL, INC. BE LIABLE FOR ANY DIRECT,
|
|
.\" INDIRECT INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
|
|
.\" (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
|
|
.\" SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
|
|
.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,
|
|
.\" STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING
|
|
.\" IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
|
|
.\" POSSIBILITY OF SUCH DAMAGE.
|
|
.\"
|
|
.\" @(#)bc.1 6.8 (Berkeley) 8/8/91
|
|
.\"
|
|
.Dd April 16, 2014
|
|
.Dt BC 1
|
|
.Os
|
|
.Sh NAME
|
|
.Nm bc
|
|
.Nd arbitrary-precision arithmetic language and calculator
|
|
.Sh SYNOPSIS
|
|
.Nm bc
|
|
.Op Fl chlv
|
|
.Op Fl e Ar expression
|
|
.Op Ar file ...
|
|
.Sh DESCRIPTION
|
|
.Nm
|
|
is an interactive processor for a language which resembles
|
|
C but provides unlimited precision arithmetic.
|
|
It takes input from any expressions on the command line and
|
|
any files given, then reads the standard input.
|
|
.Pp
|
|
Options available:
|
|
.Bl -tag -width Ds
|
|
.It Fl c
|
|
.Nm
|
|
is actually a preprocessor for
|
|
.Xr dc 1 ,
|
|
which it invokes automatically, unless the
|
|
.Fl c
|
|
.Pq compile only
|
|
option is present.
|
|
In this case the generated
|
|
.Xr dc 1
|
|
instructions are sent to the standard output,
|
|
instead of being interpreted by a running
|
|
.Xr dc 1
|
|
process.
|
|
.It Fl e Ar expression , Fl Fl expression Ar expression
|
|
Evaluate
|
|
.Ar expression .
|
|
If multiple
|
|
.Fl e
|
|
options are specified, they are processed in the order given,
|
|
separated by newlines.
|
|
.It Fl h , Fl Fl help
|
|
Prints usage information.
|
|
.It Fl l , Fl Fl mathlib
|
|
Allow specification of an arbitrary precision math library.
|
|
The definitions in the library are available to command line
|
|
expressions.
|
|
.It Fl v , Fl Fl version
|
|
Prints version information.
|
|
.El
|
|
.Pp
|
|
The syntax for
|
|
.Nm
|
|
programs is as follows:
|
|
.Sq L
|
|
means letter a-z;
|
|
.Sq E
|
|
means expression;
|
|
.Sq S
|
|
means statement.
|
|
As a non-portable extension, it is possible to use long names
|
|
in addition to single letter names.
|
|
A long name is a sequence starting with a lowercase letter
|
|
followed by any number of lowercase letters and digits.
|
|
The underscore character
|
|
.Pq Sq _
|
|
counts as a letter.
|
|
.Pp
|
|
Comments
|
|
.Bd -unfilled -offset indent -compact
|
|
are enclosed in /* and */
|
|
are enclosed in # and the next newline
|
|
.Ed
|
|
.Pp
|
|
The newline is not part of the line comment,
|
|
which in itself is a non-portable extension.
|
|
.Pp
|
|
Names
|
|
.Bd -unfilled -offset indent -compact
|
|
simple variables: L
|
|
array elements: L [ E ]
|
|
The words `ibase', `obase', and `scale'
|
|
The word `last' or a single dot
|
|
.Ed
|
|
.Pp
|
|
Other operands
|
|
.Bd -unfilled -offset indent -compact
|
|
arbitrarily long numbers with optional sign and decimal point
|
|
( E )
|
|
sqrt ( E )
|
|
length ( E ) number of significant decimal digits
|
|
scale ( E ) number of digits right of decimal point
|
|
L ( E , ... , E )
|
|
.Ed
|
|
.Pp
|
|
The sequence
|
|
.Sq \e<newline><whitespace>
|
|
is ignored within numbers.
|
|
.Pp
|
|
Operators
|
|
.Pp
|
|
The following arithmetic and logical operators can be used.
|
|
The semantics of the operators is the same as in the C language.
|
|
They are listed in order of decreasing precedence.
|
|
Operators in the same group have the same precedence.
|
|
.Bl -column "= += \-= *= /= %= ^=" "Associativity" "multiply, divide, modulus" -offset indent
|
|
.It Sy "Operator" Ta Sy "Associativity" Ta Sy "Description"
|
|
.It "++ \-\-" Ta "none" Ta "increment, decrement"
|
|
.It "\-" Ta "none" Ta "unary minus"
|
|
.It "^" Ta "right" Ta "power"
|
|
.It "* / %" Ta "left" Ta "multiply, divide, modulus"
|
|
.It "+ \-" Ta "left" Ta "plus, minus"
|
|
.It "= += -= *= /= %= ^=" Ta "right" Ta "assignment"
|
|
.It "== <= >= != < >" Ta "none" Ta "relational"
|
|
.It "!" Ta "none" Ta "boolean not"
|
|
.It "&&" Ta "left" Ta "boolean and"
|
|
.It "||" Ta "left" Ta "boolean or"
|
|
.El
|
|
.Pp
|
|
Note the following:
|
|
.Bl -bullet -offset indent
|
|
.It
|
|
The relational operators may appear in any expression.
|
|
The
|
|
.St -p1003.1-2008
|
|
standard only allows them in the conditional expression of an
|
|
.Sq if ,
|
|
.Sq while
|
|
or
|
|
.Sq for
|
|
statement.
|
|
.It
|
|
The relational operators have a lower precedence than the assignment
|
|
operators.
|
|
This has the consequence that the expression
|
|
.Sy a = b < c
|
|
is interpreted as
|
|
.Sy (a = b) < c ,
|
|
which is probably not what the programmer intended.
|
|
.It
|
|
In contrast with the C language, the relational operators all have
|
|
the same precedence, and are non-associative.
|
|
The expression
|
|
.Sy a < b < c
|
|
will produce a syntax error.
|
|
.It
|
|
The boolean operators (!, && and ||) are non-portable extensions.
|
|
.It
|
|
The boolean not
|
|
(!) operator has much lower precedence than the same operator in the
|
|
C language.
|
|
This has the consequence that the expression
|
|
.Sy !a < b
|
|
is interpreted as
|
|
.Sy !(a < b) .
|
|
Prudent programmers use parentheses when writing expressions involving
|
|
boolean operators.
|
|
.El
|
|
.Pp
|
|
Statements
|
|
.Bd -unfilled -offset indent -compact
|
|
E
|
|
{ S ; ... ; S }
|
|
if ( E ) S
|
|
if ( E ) S else S
|
|
while ( E ) S
|
|
for ( E ; E ; E ) S
|
|
null statement
|
|
break
|
|
continue
|
|
quit
|
|
a string of characters, enclosed in double quotes
|
|
print E ,..., E
|
|
.Ed
|
|
.Pp
|
|
A string may contain any character, except double quote.
|
|
The if statement with an else branch is a non-portable extension.
|
|
All three E's in a for statement may be empty.
|
|
This is a non-portable extension.
|
|
The continue and print statements are also non-portable extensions.
|
|
.Pp
|
|
The print statement takes a list of comma-separated expressions.
|
|
Each expression in the list is evaluated and the computed
|
|
value is printed and assigned to the variable `last'.
|
|
No trailing newline is printed.
|
|
The expression may also be a string enclosed in double quotes.
|
|
Within these strings the following escape sequences may be used:
|
|
.Sq \ea
|
|
for bell (alert),
|
|
.Sq \eb
|
|
for backspace,
|
|
.Sq \ef
|
|
for formfeed,
|
|
.Sq \en
|
|
for newline,
|
|
.Sq \er
|
|
for carriage return,
|
|
.Sq \et
|
|
for tab,
|
|
.Sq \eq
|
|
for double quote and
|
|
.Sq \e\e
|
|
for backslash.
|
|
Any other character following a backslash will be ignored.
|
|
Strings will not be assigned to `last'.
|
|
.Pp
|
|
Function definitions
|
|
.Bd -unfilled -offset indent
|
|
define L ( L ,..., L ) {
|
|
auto L, ... , L
|
|
S; ... S
|
|
return ( E )
|
|
}
|
|
.Ed
|
|
.Pp
|
|
As a non-portable extension, the opening brace of the define statement
|
|
may appear on the next line.
|
|
The return statement may also appear in the following forms:
|
|
.Bd -unfilled -offset indent
|
|
return
|
|
return ()
|
|
return E
|
|
.Ed
|
|
.Pp
|
|
The first two are equivalent to the statement
|
|
.Dq return 0 .
|
|
The last form is a non-portable extension.
|
|
Not specifying a return statement is equivalent to writing
|
|
.Dq return (0) .
|
|
.Pp
|
|
Functions available in the math library, which is loaded by specifying the
|
|
.Fl l
|
|
flag on the command line
|
|
.Pp
|
|
.Bl -tag -width j(n,x) -offset indent -compact
|
|
.It s(x)
|
|
sine
|
|
.It c(x)
|
|
cosine
|
|
.It e(x)
|
|
exponential
|
|
.It l(x)
|
|
log
|
|
.It a(x)
|
|
arctangent
|
|
.It j(n,x)
|
|
Bessel function
|
|
.El
|
|
.Pp
|
|
All function arguments are passed by value.
|
|
.Pp
|
|
The value of a statement that is an expression is printed
|
|
unless the main operator is an assignment.
|
|
The value printed is assigned to the special variable `last'.
|
|
This is a non-portable extension.
|
|
A single dot may be used as a synonym for `last'.
|
|
Either semicolons or newlines may separate statements.
|
|
Assignment to
|
|
.Ar scale
|
|
influences the number of digits to be retained on arithmetic
|
|
operations in the manner of
|
|
.Xr dc 1 .
|
|
Assignments to
|
|
.Ar ibase
|
|
or
|
|
.Ar obase
|
|
set the input and output number radix respectively.
|
|
.Pp
|
|
The same letter may be used as an array, a function,
|
|
and a simple variable simultaneously.
|
|
All variables are global to the program.
|
|
`Auto' variables are pushed down during function calls.
|
|
When using arrays as function arguments
|
|
or defining them as automatic variables,
|
|
empty square brackets must follow the array name.
|
|
.Pp
|
|
For example
|
|
.Bd -literal -offset indent
|
|
scale = 20
|
|
define e(x){
|
|
auto a, b, c, i, s
|
|
a = 1
|
|
b = 1
|
|
s = 1
|
|
for(i=1; 1==1; i++){
|
|
a = a*x
|
|
b = b*i
|
|
c = a/b
|
|
if(c == 0) return(s)
|
|
s = s+c
|
|
}
|
|
}
|
|
.Ed
|
|
.Pp
|
|
defines a function to compute an approximate value of
|
|
the exponential function and
|
|
.Pp
|
|
.Dl for(i=1; i<=10; i++) e(i)
|
|
.Pp
|
|
prints approximate values of the exponential function of
|
|
the first ten integers.
|
|
.Bd -literal -offset indent
|
|
$ bc -l -e 'scale = 500; 2 * a(2^10000)' -e quit
|
|
.Ed
|
|
.Pp
|
|
prints an approximation of pi.
|
|
.Sh COMMAND LINE EDITING
|
|
.Nm
|
|
supports interactive command line editing, via the
|
|
.Xr editline 3
|
|
library.
|
|
It is enabled by default if input is from a tty.
|
|
Previous lines can be recalled and edited with the arrow keys,
|
|
and other GNU Emacs-style editing keys may be used as well.
|
|
.Pp
|
|
The
|
|
.Xr editline 3
|
|
library is configured with a
|
|
.Pa .editrc
|
|
file \- refer to
|
|
.Xr editrc 5
|
|
for more information.
|
|
.Sh FILES
|
|
.Bl -tag -width /usr/share/misc/bc.library -compact
|
|
.It Pa /usr/share/misc/bc.library
|
|
math library, read when the
|
|
.Fl l
|
|
option is specified on the command line.
|
|
.El
|
|
.Sh COMPATIBILITY
|
|
The
|
|
.Fl q
|
|
and
|
|
.Fl Fl quiet
|
|
options are no-ops for compatibility with some other implementations of
|
|
.Nm
|
|
and their use is discouraged.
|
|
.Sh SEE ALSO
|
|
.Xr dc 1
|
|
.Sh STANDARDS
|
|
The
|
|
.Nm
|
|
utility is compliant with the
|
|
.St -p1003.1-2008
|
|
specification.
|
|
.Pp
|
|
The flags
|
|
.Op Fl ce ,
|
|
as well as the parts noted above,
|
|
are extensions to that specification.
|
|
.Sh HISTORY
|
|
The
|
|
.Nm
|
|
command first appeared in
|
|
.At v6 .
|
|
A complete rewrite of the
|
|
.Nm
|
|
command first appeared in
|
|
.Ox 3.5 .
|
|
.Sh AUTHORS
|
|
.An -nosplit
|
|
The original version of the
|
|
.Nm
|
|
command was written by
|
|
.An Robert Morris
|
|
and
|
|
.An Lorinda Cherry .
|
|
The current version of the
|
|
.Nm
|
|
utility was written by
|
|
.An Otto Moerbeek .
|
|
.Sh BUGS
|
|
.Ql Quit
|
|
is interpreted when read, not when executed.
|
|
.Pp
|
|
Some non-portable extensions, as found in the GNU version of the
|
|
.Nm
|
|
utility are not implemented (yet).
|