1BAS(1) General Commands Manual BAS(1)
2
6 bas - basic
7
9 bas [ file ]
10
12 Bas is a dialect of Basic. If a file argument is provided, the file is
13 used for input before the terminal is read. Bas accepts lines of the
14 form:
15 statement
17 integer statement
18 Integer numbered statements (known as internal statements) are stored
20 for later execution. They are stored in sorted ascending order. Non-
21 numbered statements are immediately executed. The result of an immedi‐
22 ate expression statement (that does not have `=' as its highest opera‐
23 tor) is printed. Interrupts suspend computation.
24 Statements have the following syntax:
26 expression
28 The expression is executed for its side effects (assignment or
29 function call) or for printing as described above.
30 comment
32 This statement is ignored. It is used to interject commentary in
33 a program.
34 done
36 Return to system level.
37 dump
39 The name and current value of every variable is printed.
40 edit
42 The UNIX editor, ed, is invoked with the file argument. After the
43 editor exits, this file is recompiled.
44 for name = expression expression statement
46 for name = expression expression
47 next
48 The for statement repetitively executes a statement (first form)
49 or a group of statements (second form) under control of a named
50 variable. The variable takes on the value of the first expres‐
51 sion, then is incremented by one on each loop, not to exceed the
52 value of the second expression.
53 goto expression
55 The expression is evaluated, truncated to an integer and execution
56 goes to the corresponding integer numbered statment. If executed
57 from immediate mode, the internal statements are compiled first.
58 if expression statement
60 if expression
61 [ else
62 fi
63 The statement (first form) or group of statements (second form) is
64 executed if the expression evaluates to non-zero. In the second
65 form, an optional else allows for a group of statements to be exe‐
66 cuted when the first group is not.
67 list [expression [expression]]
69 is used to print out the stored internal statements. If no argu‐
70 ments are given, all internal statements are printed. If one
71 argument is given, only that internal statement is listed. If two
72 arguments are given, all internal statements inclusively between
73 the arguments are printed.
74 print list
76 The list of expressions and strings are concatenated and printed.
77 (A string is delimited by " characters.)
78 prompt list
80 Prompt is the same as print except that no newline character is
81 printed.
82 return [expression]
84 The expression is evaluated and the result is passed back as the
85 value of a function call. If no expression is given, zero is
86 returned.
87 run
89 The internal statements are compiled. The symbol table is re-ini‐
90 tialized. The random number generator is reset. Control is
91 passed to the lowest numbered internal statement.
92 save [expression [expression]]
94 Save is like list except that the output is written on the file
95 argument. If no argument is given on the command, b.out is used.
96 Expressions have the following syntax:
98 name
100 A name is used to specify a variable. Names are composed of a
101 letter followed by letters and digits. The first four characters
102 of a name are significant.
103 number
105 A number is used to represent a constant value. A number is writ‐
106 ten in Fortran style, and contains digits, an optional decimal
107 point, and possibly a scale factor consisting of an e followed by
108 a possibly signed exponent.
109 ( expression )
111 Parentheses are used to alter normal order of evaluation.
112 _ expression
114 The result is the negation of the expression.
115 expression operator expression
117 Common functions of two arguments are abbreviated by the two argu‐
118 ments separated by an operator denoting the function. A complete
119 list of operators is given below.
120 expression ( [expression [ , expression] ... ] )
122 Functions of an arbitrary number of arguments can be called by an
123 expression followed by the arguments in parentheses separated by
124 commas. The expression evaluates to the line number of the entry
125 of the function in the internally stored statements. This causes
126 the internal statements to be compiled. If the expression evalu‐
127 ates negative, a builtin function is called. The list of builtin
128 functions appears below.
129 name [ expression [ , expression ] ... ]
131 Each expression is truncated to an integer and used as a specifier
132 for the name. The result is syntactically identical to a name.
133 a[1,2] is the same as a[1][2]. The truncated expressions are
134 restricted to values between 0 and 32767.
135 The following is the list of operators:
137 = = is the assignment operator. The left operand must be a name
139 or an array element. The result is the right operand. Assign‐
140 ment binds right to left,
141 & | & (logical and) has result zero if either of its arguments are
143 zero. It has result one if both its arguments are non-zero. |
144 (logical or) has result zero if both of its arguments are zero.
145 It has result one if either of its arguments are non-zero.
146 < <= > >= == <>
148 The relational operators (< less than, <= less than or equal, >
149 greater than, >= greater than or equal, == equal to, <> not
150 equal to) return one if their arguments are in the specified
151 relation. They return zero otherwise. Relational operators at
152 the same level extend as follows: a>b>c is the same as a>b&b>c.
153 + - Add and subtract.
155 * / Multiply and divide.
157 ^ Exponentiation.
159 The following is a list of builtin functions:
161 arg(i) is the value of the i -th actual parameter on the current level
163 of function call.
164 exp(x) is the exponential function of x.
166 log(x) is the natural logarithm of x.
168 sqr(x) is the square root of x.
170 sin(x) is the sine of x (radians).
172 cos(x) is the cosine of x (radians).
174 atn(x) is the arctangent of x. Its value is between -π/2 and π/2.
176 rnd( ) is a uniformly distributed random number between zero and one.
178 expr( )
180 is the only form of program input. A line is read from the
181 input and evaluated as an expression. The resultant value is
182 returned.
183 abs(x) is the absolute value of x.
185 int(x) returns x truncated (towards 0) to an integer.
187
189 /tmp/btm? temporary
190 b.out save file
191 /bin/ed for edit
192
194 Syntax errors cause the incorrect line to be typed with an underscore
195 where the parse failed. All other diagnostics are self explanatory.
196
198 Has been known to give core images.
199 Catches interrupts even when they are turned off.
200 BAS(1)