bas_files.1

' t
.TH BAS 1 "August 23, 2017" "" "File Statements"
.SH NAME \"{{{roff}}}\"{{{
bas \- BASIC interpreter (pw)
.\"}}}
.SH SYNOPSIS \"{{{
.ad l
.B bas
.RB [ \-a ]
.RB [ \-b ]
.RB [ \-c ]
.RB [ \-l
.IR file ]
.RB [ \-n ]
.RB [ \-r ]
.RB [ \-u ]
.RI [ "program " [ argument "...]]"
.br
.B bas
.RB [ \-\-autoexec ]
.RB [ \-\-backslash\-colon ]
.RB [ \-\-color256 ]
.RB [ \-\-lp
.IR file ]
.RB [ \-\-no\-end\-program ]
.RB [ \-\-restricted ]
.RB [ \-\-uppercase ]
.RI [ "program " [ argument "...]]"
.br
.B bas
.BR \-h | \-\-help
.br
.B bas
.BR \-\-version
.ad b
.\"}}}
.SH DESCRIPTION \"{{{
.SS "File Statements" \"{{{
Each line of a BASIC program contains one or more of the statements below.
Multiple statements are grouped by a colon (\fB:\fP) in between them.
.IP "\fBchain\fP [\fIfile$\fP]" \"{{{
Chain program \fIfile$\fP execution (with current variables). Unlike RUN
it does not perform a NEW internally.
.\"}}}
.IP "\fBchdir\fP \fIdirectory$\fP" \"{{{
Change the current directory to \fIdirectory$\fP.
.\"}}}
.IP "\fBclose\fP [\fB#\fP\fIchannel%\fP{\fB,#\fP\fIchannel%\fP}]" \"{{{
Close the specified channels.  If no channels are given, all channels
but the standard input/output channel \fB#0\fP are closed.
.\"}}}
.IP "\fBcopy\fP \fIfrom$\fP \fBto\fP \fIto$\fP" \"{{{
Copy a file.
.\"}}}
.IP "\fBdisplay\fP \fIfilename$\fP" \"{{{
Display the contents of \fIfilename$\fP on standard output, like
.IR cat (1)
does. This command uses carrage return as the end of line character.
.\"}}}
.IP "\fBfield\fP [\fB#\fP]\fIchannel%\fP\fB,\fP\fIwidth\fP \fBas\fP \fIlvalue$\fP {\fB,\fP\fIwidth\fP \fBas\fP \fIlvalue$\fP}" \"{{{
Allocate \fIwidth\fP bytes in the record buffer to the \fIlvalue$\fP.
The total number of allocated bytes must not exceed the record length.
The same record buffer can be allocated to different lvalues
by using multiple field statements.  Fielded lvalues must be set
with \fBlset\fP and \fBrset\fP.  Simple assignments to them will cause
different storage to be allocated to them, thus not effecting the random
access buffer.
.\"}}}
.IP "\fBget\fP [\fB#\fP]\fIchannel%\fP [\fB,\fP\fIrecord\fP]" \"{{{
Read the record buffer of \fIchannel%\fP from the file it is connected to,
which must be opened in \fBrandom\fP mode.  If a \fIrecord\fP number is
given, the record is read there instead of being read from the current
record position.  The first record is 1.
.\"}}}
.IP "\fBget\fP [\fB#\fP]\fIchannel%\fP\fB,\fP[\fIposition\fP]\fB,\fP\fIlvalue\fP" \"{{{
Read the \fIlvalue\fP from the specified channel, which must be opened in
\fBbinary\fP mode.  If a \fIposition\fP is given, the data is read there
instead of being read from the current position.  The first position is 1.
.\"}}}
.IP "\fBinput\fP [\fB#\fP\fIchannel%\fP\fB,\fP][\fB;\fP][\fIstring\fP[\fB;\fP|\fB,\fP|\fB:\fP]]\fIlvalue\fP{\fB,\fP\fIlvalue\fP}" \"{{{
The \fBinput\fP statement prints the optional prompt \fIstring\fP and
a trailing question mark (\fB?\fP).  After, it reads comma separated
values and assigns them to the given variables.  If too few values are
typed in, missing values will be requested with the prompt \fB??\fP.
An empty value for a numeric variable means zero.  If too much input
data is given, a warning is printed.  If a channel other
than \fB#0\fP is specified, no question marks or error messages will be
printed, instead an error is returned.  A semicolon before the prompt
will not move the cursor to a new line after pressing RETURN.  If the
prompt is followed by a comma, colon or no punctuation at all, no question mark will
be printed after the prompt.  \fBNote\fP: Some dialects allow a string
expression instead of the \fIstring\fP.
.\"}}}
.IP "\fBkill\fP \fIfilename$\fP" \"{{{
Delete a file.
.\"}}}
.IP "[\fBlet\fP] \fIlvalue\fP{\fB,\fP\fIlvalue\fP} \fB=\fP \fIexpression\fP" \"{{{
Evaluate the \fIexpression\fP and assign its value to each \fIlvalue\fP,
converting it, if needed.
\fILvalues\fP are variables or array variable elements.  All assignments
are performed independently of each other.
.\"}}}
.IP "\fBline input\fP [\fB#\fP\fIchannel%\fP\fB,\fP][\fIstring\fP\fB;\fP|\fB,\fP]\fIlvalue$\fP" \"{{{
The \fBline input\fP statement prints the optional prompt \fIstring\fP,
reads one line of input and assigns unmodified it to the \fIlvalue$\fP.
Using a comma instead of a semicolon makes no difference with this
statement.
.\"}}}
.IP "\fBload\fP [\fIfile$\fP]" \"{{{
Load the program \fIfile$\fP (direct mode only).  The name may
be omitted to load a program of the name used by a previous \fBload\fP
or \fBsave\fP statement.
.\"}}}
.IP "\fBlock\fP [\fB#\fP]\fIchannel%\fP" \"{{{
Wait for an exclusive lock on the file associated with the \fIchannel%\fP
to be granted.
.\"}}}
.IP "\fBlset\fP \fIvariable$\fP\fB=\fP\fIexpression\fP" \"{{{
Store the left adjusted \fIexpression\fP value in the storage
currently occupied by the \fIvariable$\fP.  If the storage does not suffice,
the \fIexpression\fP value is truncated, if its capacity exceeds the length
of the \fIexpression\fP value, it is padded with spaces.
.\"}}}
.IP "\fBrset\fP \fIvariable$\fP\fB=\fP\fIexpression\fP" \"{{{
Store the right adjusted \fIexpression\fP value in the storage currently
occupied by the \fIvariable$\fP, padding with spaces from the right if
the storage capacity exceeds the length of the \fIexpression\fP value.
.\"}}}
.IP "\fBmerge\fP [\fIfile$\fP]" \"{{{
Merge program \fIfile$\fP with current listing (direct mode only). Unlike LOAD
it does not perform a NEW internally.
.\"}}}
.IP "\fBmkdir\fP \fIdirectory$\fP" \"{{{
Create a \fIdirectory$\fP.
.\"}}}
.IP "\fBname\fP \fIoldname$\fP \fBas\fP \fInewname$\fP" \"{{{
Rename the file \fIoldname$\fP to \fInewname$\fP.
.\"}}}
.IP "\fBopen\fP \fImode$\fP\fB,\fP[\fB#\fP]\fIchannel%\fP\fB,\fP\fIfile$\fP[\fB,\fP\fIlength\fP]" \"{{{
Open the \fIfile$\fP through the \fIchannel%\fP.  The mode must be
\fB"i"\fP for input, \fB"o"\fP for output, \fB"a"\fP for appending
output or \fB"r"\fP for random access.  Opening the file for random
access requires the record \fIlength\fP to be specified.  This syntax
is used by MBASIC and some other interpreters.
.\"}}}
.IP "\fBopen\fP \fIfile$\fP [\fBfor\fP \fBinput\fP|\fBoutput\fP|\fBappend\fP|\fBrandom\fP|\fBbinary\fP] [\fBaccess\fP \fBread\fP|\fBwrite\fP|\fBread write\fP] [\fBshared\fP|\fBlock read\fP|\fBlock write\fP] \fBas file\fP [\fB#\fP]\fIchannel%\fP [\fBlen=\fP\fIlength%\fP]" \"{{{
Open the \fIfile$\fP through the \fIchannel%\fP.  Files opened in
\fBinput\fP mode must already exist, whereas the other methods create
them as needed.  If the file is opened for random access and no record
\fIlength\fP is specified, a record length of 1 is used.  This is the
ANSI BASIC syntax found in more modern programs.  The \fBbinary\fP mode
is similar to \fBrandom\fP mode, but there is no fixed record length:
Data is read and written directly using \fBget\fP and \fBput\fP without
using \fBfield\fP.  If no open method is specified, the file is opened
as \fIrandom\fP.  Optionally, a file access mode can be specified.
.IP
The file locking implementations vary greatly between dialects: Some
implementations offer independent locks for reading and writing,
others offer shared locks (usually used for many readers) and
exclusive locks (usually used for writers).  Additionally, locks may
be advisory/cooperative or mandatory.  Most dialects use exclusive
locks of highest protection by default.  \fBBas\fP implements POSIX
shared/exclusive locks, which are usually advisory, and offers the
following:
.RS
.IP \fBshared\fP
any process can read or write file
.IP "\fBlock read\fP"
shared lock, \fBopen\fP fails if file is locked exclusively
.IP "\fBlock write\fP
exclusive lock
.IP "default"
no lock is taken, same as \fBshared\fP
.RE
.IP
Programs using locks may fail if the dialect they were written for
had different lock semantics!
.\"}}}
.IP "[\fBl\fP]\fBprint\fP [\fB#\fP\fIchannel%\fP[\fB,\fP]][\fBusing\fP \fIformat\fP\fB;\fP]{\fIexpression\fP|\fBtab(\fP\fIposition\fP\fB)\fP|\fBspc(\fP\fIlength\fP\fB)\fP|\fB;\fP|\fB,\fP}" \"{{{
Evaluate the expressions and print their values to the integral
expression \fIchannel%\fP.  If no channel is given, the standard output
channel \fB#0\fP will be used.  The statement \fBlprint\fP prints to the
printer channel and no other channel can be specified.  The \fBusing\fP
format string or line may contain the following characters:
.RS
.IP "\fB_\fP"
Print the following character instead of interpreting it as formatting
command.
.IP "\fB!\fP"
Print the first character of a string.
.IP "\fB\e\fP"
Print two more characters of a string as there are
spaces between the backslashes.
.IP "\fB&\fP"
Print a string without any formatting.  Note: Some BASIC dialects use
\fB&\fP characters to specify the string width.  A single \fB&\fP would
only print the first character in those dialects.  In other dialects,
an ampersand represents one digit of the numeric format, padding the
number with zeroes.
.IP "\fB+\fP"
A plus at the beginning or end of a numeric format causes the sign to
be printed at the beginning or the end.
.IP "\fB\-\fP"
A minus at the end of a numeric format prints a trailing minus after
negative numbers and a space else.
.IP "\fB,\fP"
A comma inside the integral part of a numeric format inserts a comma
before each three-digit group of the integral part of the number.
It also represents one digit in the format.  Although one comma suffices,
it makes formats more readable to insert a comma every three digits.
.IP "\fB#\fP"
Each hash sign represents one digit of the numeric format.  If there
are fewer digits in the integral part of the value, it is preceded by
spaces.
.IP "\fB^\fP"
Each caret represents one digit of the exponent.  At least three carets
are required, because the exponent is leaded by an \fBE\fP and the
epxonent sign is always printed.  The number is printed in the numeric
format asked for by hash signs with the exponent adjusted accordingly,
e.g. printing \fB5\fP using \fB###.##^^^^^\fP results in \fB500.00E-002\fP.
.IP "\fB*\fP"
Like a hash sign, but the number will not be preceded by spaces, but
by asterisks.
.IP "\fB0\fP"
Like a hash sign, but the number will not be preceded by spaces, but
by zeroes.
.IP "\fB.\fP"
The dot specifies the position of the decimal point between a
pound/asterisk sign group for the integral value and an optional pound
sign group for the precision of the fractional part.
.IP "\fB$\fP"
A dollar sign prefixes the number with a dollar.  Further dollar signs
increase the numeric width like \fB#\fP and \fB*\fP.  If the dollar sign
stands in front of all padding, it will precede it, otherwise it will be
printed after any padding.
.IP "any other character"
Any other character is printed literally and separates different numeric
fields of a multi-field format.
.RE
.IP
If no format is given, positive values are printed with a heading space,
negative values are printed with a heading minus, the precision is set
as required and the number is followed by a space.  \fBprint\fP without
\fBusing\fP will advance to the next line if the value of the expression
no longer fits into the current line.
.IP
A semicolon concatenates the output while a comma puts the values in
columns.  A trailing semicolon suppresses printing a trailing newline.
The pseudo function \fBtab\fP, which must only be used within \fBprint\fP
statements, spaces to the specified print position (column) with 0 being
the leftmost position.  If the current print position is already beyond
\fIvalue\fP, it does nothing.  If \fIvalue\fP is beyond the output width,
advancing the position stops there.  The pseudo function \fBspc\fP is similar
to \fBtab\fP, but it prints as many spaces as specified by its argument.
Abbreviation: \fB?\fP or \fBp.\fP
.\"}}}
.IP "\fBput\fP [\fB#\fP]\fIchannel%\fP [\fB,\fP\fIrecord\fP]" \"{{{
Write the record buffer of \fIchannel%\fP to the file it is connected to,
which must be opened in \fBrandom\fP mode.  If a \fIrecord\fP number
is given, the record is written there instead of being written to the
current record position.
.\"}}}
.IP "\fBput\fP [\fB#\fP]\fIchannel%\fP\fB,\fP[\fIposition\fP]\fB,\fP\fIvalue\fP" \"{{{
Write the \fIvalue\fP to the specified channel, which must be opened
in \fBbinary\fP mode.  If a \fIrecord\fP number is given, the data is
written there instead of being written to the current position.
.\"}}}
.IP "\fBrename\fP \fIfrom$\fP \fBto\fP \fIto$\fP" \"{{{
Rename a file.
.\"}}}
.IP "\fBrun\fP [\fIline\fP|\fIfile$\fP]" \"{{{
Compile the program, clear all variables, close all files and start program execution.
If a file is specified, the file is loaded first and run from the
beginning.  If a line is specified, execution starts at the given
line.
.\"}}}
.IP "\fBsave\fP [\fIfile$\fP]" \"{{{
Save the program to the given \fIfile$\fP (direct mode only).  The name may
be omitted to save the program under the name used by a previous \fBload\fP
or \fBsave\fP statement.
.\"}}}
.IP "\fBshell\fP [\fIcommand$\fP]" \"{{{
If a \fIcommand$\fP is given, it is executed as child process of
\fBbas\fP as bourne shell command.  If used without a \fIcommand$\fP,
the shell specified by the environment variable \fBSHELL\fP (defaults
to the bourne shell if not set) is started without arguments.
.\"}}}
.IP "\fBtruncate\fP [\fB#\fP]\fIchannel%\fP" \"{{{
Truncate the file after the current position.  The file must be opened with
write access.
.\"}}}
.IP "\fBunlock\fP [\fB#\fP]\fIchannel%\fP" \"{{{
Release any locks on the file associated with the \fIchannel%\fP.
.\"}}}
.IP "\fBwrite\fP [\fB#\fP\fIchannel%\fP[\fB,\fP]]{\fIexpression\fP|\fB,\fP|\fB;\fP}" \"{{{
Write the values of the given expressions to the specified channel or
to standard output if no channel is given.  Different expressions are
separated by commas and a newline is written at the end of the list.
Strings will be written enclosed in double quotes and positive numbers
are not written with a heading blank.
.\"}}}
.\"}}}
.SS "Expressions and Functions" \"{{{
Expressions consist of operators or functions that act on integer,
real (floating point) or string values.  Beside decimal notation,
integer values can be written as hexadecimal values by prefixing them
with \fB&h\fP and as octal values by prefixing them with \fB&o\fP, 
and now as binary values by prefixing them with \fB&b\fP.
String constants may contain paired double quotes to specify double quote
characters inside strings.  If the constant is terminated by the end of
the line, the trailing double quote can be omitted.  Numeric constants
with the suffix \fB#\fP or \fB!\fP are always regarded as floating point
constants, \fBbas\fP ignores the precision specification, because it
does not offer different precisions.  Integer constants may be followed
by the suffix \fB%\fP.  If an integer literal is outside the integer
value range, it is treated as a floating point literal.
.PP
The table below shows the available operators with decreasing priority.
The operator \fB=>\fP is converted to \fB>=\fP, \fB=<\fP is converted
to \fB<=\fP and \fB><\fP is converted to \fB<>\fP when programs are loaded.
.PP
.TS
box,center;
c l
cfB l.
operator	meaning
_
^	exponentiation
_
\-	unary negation
+	unary plus
_
*	multiplication
/	floating-point division
\e	integer division (equal to fix(a/b))
mod	modulo
_
+	addition, string concatenation
\-	substraction
_
>	greater than
>=	greater than or equal to
\&=	equal to
<>	not equal to
<=	less than or equal to
<	less than
_
not	binary complement
_
and	binary and
_
or	binary or
xor	binary exclusive or
eqv	binary equivalent
imp	binary implication
.TE
.sp .5v
.PP
Besides operators, various builtin functions can be used in expressions.
The dollar character (\fB$\fP) denotes that the argument must be of
the type string.  The actual parameters of functions, both builtin
and user-defined, as well as subroutines, are passed by value.  Note:
Modern (not old) ANSI BASIC passes actual parameters by reference.
Many classic dialects don't offer call by reference and \fBbas\fP
follows that direction.  Arguments to functions and subroutines must
be enclosed in parentheses.  Note: Some dialects allow to omit them,
which introduces ambiguity in some cases.
.PP
Listed here are only the functions that relate to file statements
.IP "\fBcommand$\fP"
Return extra command line arguments after the program name, separated
by spaces.  The program name is not part of the return value.  Note:
This function is implemented for compatibility and does not deal with
arguments with embedded spaces.
.IP "\fBcommand$(\fP\fIn%\fP\fB)\fP"
Return the \fIn%\fPth argument passed to the program, starting with 1.
The first returned argument (index 0) is the program name.
.IP "\fBedit$(\fP\fIstring$\fP\fB,\fP\fIcode%\fP\fB)\fP"
Return the result of editing the \fIstring$\fP as indicated by the \fIcode%\fP.
The following editing codes are available:
.RS
.IP 1
discard parity bit
.IP 2
discard all spaces and tabs
.IP 4
discard all carriage returns, line feeds, form feeds,
deletes, escapes and nulls
.IP 8
discard leading spaces and tabs
.IP 16
convert multiple spaces and tabs to one space
.IP 32
convert lower case to upper case
.IP 64
convert left brackets to left parentheses and right
brackes to right parentheses
.IP 128
discard trailing spaces and tabs
.IP 256
suppress all editing for characters within matching
single or double quotes.  If the matching quote is missing,
suppress all editing up to the end of the string.
.RE
.IP
The codes can be added for combined editing operations.
.IP "\fBenviron$(\fP\fIn%\fP\fB)\fP"
Return the \fIn%\fPth environment entry in the form
\fIvariable\fP\fB=\fP\fIvalue\fP, starting with 1.  If \fIn%\fP is larger
than the number of entries, an empty string is returned.
.IP "\fBenviron$(\fP\fIvariable$\fP\fB)\fP"
Return the value of the specified environment \fIvariable$\fP.  If there
is no such variable, an empty string is returned.
.IP "\fBeof(\fP\fIchannel%\fP\fB)\fP"
Return true if the end of the channel has been reached.  This must be
used to avoid that \fBinput\fP tries to read past the end of a file.
.IP "\fBerl\fP"
Return the number of the line where the last exception was thrown.
.IP "\fBerr\fP"
Return a numeric code for the last exception that was thrown.  The use
of this function is not portable.
.IP "\fBfalse\fP"
Return 0.
.IP "\fBfind$(\fP\fIpattern$\fP[\fB,\fP\fInth%\fP]\fB)\fP
Return the first (or \fInth%\fP, starting from 0, if specified) filename
that matches the given pattern or the empty string, if no filename
matches the pattern.  This function is usually used to check for the
existance of a file.  The pattern may use the wildcards \fB*\fP to match
an arbitrary number of characters and \fB?\fP to match a single character.
Note: On some systems, the star does not match a dot inside a filename.
In this implementation, the star matches everything and \fB*.*\fP only
matches files with a dot in their name, not files without an extension.
Some systems also encode file attributes in the eigth bit of the
file name and programs strip that bit from the output of \fBfind$\fP.
It is recommended to use only 7-bit file names with applications using
this function.
.IP "\fBfreefile\fP"
Return the first free file handle.
.IP "\fBinput$(\fP\fIlength\fP[\fB,\fP\fIchannel\fP]\fB)\fP"
Read a string of \fIlength\fP characters from standard input or from
the specified \fIchannel\fP.  The characters will not be echoed.
.IP "\fBloc(\fP\fIchannel%\fP\fB)\fP"
If used on random-access files, the number of the last accessed record
is returned.  For sequential files, the current read/write position is
returned.  Note: Some BASIC dialects return the record position in bytes
and the read/write position in pseudo-records.
.IP "\fBlof(\fP\fIchannel%\fP\fB)\fP"
Return the size of the file that is attached to the channel (bytes
for sequential or binary files, records for random-access files).
This may not work correctly for files with sizes that exceed the range
of integer numbers.  Note: Some BASIC dialects return the number of
bytes even for random-access files.
.IP "\fBtrue\fP"
Return \-1.
.IP "\fBval(\fP\fIstring$\fP\fB)\fP"
If possible, then convert the \fIstring$\fP into an integer or floating
point value, ignoring trailing junk.  Otherwise, return 0.0.  Like
anywhere else, hexadecimal values are specified by a leading \fB&h\fP.
.\"}}}
.\"}}}
.SH EXAMPLES \"{{{
.SS "Load text file lines into a variable" \"{{{
.TS
box,left;
cfB l.
1000	dim Text$(1000) : maxLines=0
2000	open "file.txt" for input as #1
2010	while not eof(1)
2020	  inc maxLines
2030	  line input #1,Text$(maxLines)
2040	wend
2050	close #1
.TE
.PP
Here we dimension the zero (0) based string array 
.B Text$ 
to 1000.
.B maxLines 
holds the number or lines read from the text file, with
.B Text$(0)=""
which helps because 1 is the first line that can be printed to
using 
.B LOCATE y,x 
while
.B maxLines 
allows us to easily find the last line of text.
.\"}}}
.SS "Load and set text screen dimensions" \"{{{
.TS
box,left;
cfB l.
20	LINES=24 : if environ$("LINES")<>"" then LINES=val(environ$("LINES"))
21	COLUMNS=80 : if environ$("COLUMNS")<>"" then COLUMNS=val(environ$("COLUMNS"))
22	width COLUMNS
.TE
.PP
The environment variable 
.B LINES 
is a text variable so we must get its value using the
.B VAL(string$)
function. Most shells or terminals will set these variables, but for
.B Bas 
to be able to read them they must be present in the output from the 
.B env 
command (ie. present in SH, not just BASH). Place the following lines
at the top of  
.B /etc/profile
.PP
.TS
x,left;
cfB l.
 	# export some BASH vars (set) to SH (env) (for 'bas')
 	export LINES=$LINES
 	export COLUMNS=$COLUMNS
 	export EDITOR=`which vim.tiny`

 	# normal profile stuff
 	 
.TE
.\"}}}
.SS "Load and print a text file" \"{{{
.TS
box,left;
cfB l.
1000	textLine$="" : l=0
2000	open "file.txt" for input as #1
2010	while not eof(1)
2020	  inc l
2030	  line input #1,textLine$
2040	  print textLine$
2050	  if l=24 then
2060	    l=0
2070	    x$=inkey$ : if x$="" then goto 2070
2080	  end
2090	wend
2100	close #1
.TE
.PP
Here we wait for a key press every 24 lines
.\"}}}
.SS "Using pipes to get SHELL results" \"{{{
.TS
box,left;
cfB l.
3000	cmd$="cat /proc/meminfo | grep MemFree"
3010	shell cmd$
.TE
.PP
Here we pipe the output of one shell command as the input for the next command, 
using the 
.B "|"
(usually SHIFT+\\) pipe character.
.\"}}}
.SS "Using files to get SHELL results" \"{{{
.TS
box,left;
cfB l.
1000	mem_gpu=0 : mem_cpu=0 : mem_fre=0 :fl=0 : x$="" : dim fre(0)
4000	cmd$="vcgencmd get_mem gpu > /var/temp/.bas.mem"
4001	shell cmd$
4010	cmd$="vcgencmd get_mem arm >> /var/temp/.bas.mem"
4011	shell cmd$
4020	cmd$="cat /proc/meminfo | grep MemFree >> /var/temp/.bas.mem"
4021	shell cmd$
4050	open "/var/temp/.bas.mem" for input as #1
4060	while not eof(1)
4070	  inc fl : x$=""
4071	  line input #1,x$
4080	  if fl=1 then mem_gpu=val(mid$(x$,5,(len(x$)-5)))*1024
4081	  if fl=2 then mem_cpu=val(mid$(x$,5,(len(x$)-5)))*1024
4082	  if fl=3 then mem_fre=val(ltrim$(mid$(x$,9,(len(x$)-11))))
4090	wend
4100	close #1
4110	print "GPU memory:";mem_gpu;"Kb"
4120	print "CPU memory:";mem_cpu;"Kb"
4130	print "Free memory:";mem_fre;"Kb" : fre(0)=mem_fre
.TE
.PP
Here we pipe three(3) results to the temporary file
.B /var/temp/.bas.mem
then read them back one line at a time, converting them to integers as we go.
.B fre(0)
uses a one dimension array to fake the MSX-BASIC function. Note that
.B fre(n)
where 
.B n>0
will generate an error using this method.
.\"}}}
.SS "Manipulating SHELL results" \"{{{
.TS
box,left;
cfB l.
1000	filename$="autoexec.bas"
3000	cmd$="file "+filename$+"|grep 'ASCII text'>/var/temp/.bas.file" : shell cmd$
3010	open "/var/temp/.bas.file" for input lock read as #1
3011	f$=""
3020	if not eof(1) then line input #1,f$
3030	close #1
3040	if f$="" then
3050	  color 14,12,12 : print filename$;" is not ASCII text"
3070	else
3080	  print filename$;" is ";f$
3090	end if
3100	color 15,1,1
.TE
.PP
Here we will only get a result if the text string "ASCII text" is present in the first line output by the
.B file
command, which can use some magic to determine an exact file type.
.\"}}}
.\"}}}
.SH OPTIONS \"{{{
.IP "\fB\-a\fP, \fB\-\-autoexec\fP"
From the folder \fBBas\fP is started from, first perform \fBRUN "./autoexec.bas"\fP
in the current directory.
.IP "\fB\-b\fP, \fB\-\-backslash\-colon\fP"
Convert backslashs to colons.  By default, a backslash is the operator
for integer division, but in some BASIC dialects it forms compound
statements as the colon does.
.IP "\fB\-c\fP, \fB\-\-color256\fP"
Allows 256 colors instead of 16. The terminal (\fB\TERM\fP) must support it.
.IP "\fB\-l\fP \fIfile\fP, \fB\-\-lp\fP \fIfile\fP"
Write \fBLLIST\fP and \fBLPRINT\fP output to \fIfile\fP.  By default,
that output will be written to \fB/dev/null\fP.
.IP "\fB\-n\fP, \fB\-\-no\-end\-program\fP"
Prevents 
.B END program
from being printed
.IP "\fB\-r\fP, \fB\-\-restricted\fP"
Restricted operation which does not allow to fork a shell.
.IP "\fB\-u\fP, \fB\-\-uppercase\fP"
Output all tokens in uppercase.  By default, they are lowercase,
which is easier to read, but some BASIC dialects require uppercase.
This option allows to save programs for those dialects.
.IP "\fB\-h\fP, \fB\-\-help\fP"
Output usage and exit.
.IP "\fB\-v\fP, \fB\-\-version\fP"
Display version information and exit.
.\"}}}
.SH AUTHOR \"{{{
This program is copyright 1999\(en2014 Michael Haardt
<michael@moria.de>.
.PP
Custom MAN pages & MSX-BASIC extensions copyright 2017 Paul Wratt 
<paul.wratt@gmail.com>
.PP
Permission is hereby granted, free of charge, to any person obtaining a copy
of this software and associated documentation files (the "Software"), to deal
in the Software without restriction, including without limitation the rights
to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
copies of the Software, and to permit persons to whom the Software is
furnished to do so, subject to the following conditions:
.PP
The above copyright notice and this permission notice shall be included in
all copies or substantial portions of the Software.
.PP
THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
THE SOFTWARE.
.\"}}}
.SH HISTORY \"{{{
There has been a \fIbas\fP(1) command in UNIX v7, but its syntax
was strongly influenced by C, unlike common classic BASIC dialects, and
thus not compatible with this implementation. MSX-BASIC is an extension
of Microsoft BASIC v4.0.
.\"}}}
.SH "SEE ALSO" \"{{{
The Usenet group comp.lang.basic.misc discusses the classic BASIC dialect.
.\"}}}