fmlexpr(1F) FMLI Commands fmlexpr(1F)NAMEfmlexpr - evaluate arguments as an expression
SYNOPSISfmlexpr arguments
DESCRIPTION
The fmlexpr function evaluates its arguments as an expression. After
evaluation, the result is written on the standard output. Terms of the
expression must be separated by blanks. Characters special to FMLI
must be escaped. Note that 30 is returned to indicate a zero value,
rather than the null string. Strings containing blanks or other special
characters should be quoted. Integer-valued arguments may be preceded
by a unary minus sign. Internally, integers are treated as 32-bit, 2s
complement numbers.
The operators and keywords are listed below. Characters that need to be
escaped are preceded by \. The list is in order of increasing prece‐
dence, with equal precedence operators grouped within {} symbols.
USAGE
Expressions
expr \| expr
Returns the first expr if it is neither NULL nor 0, otherwise
returns the second expr.
expr \& expr
Returns the first expr if neither expr is NULL or 0, otherwise
returns 0.
expr { =, \>, \>=, \<, \<=, != } expr
Returns the result of an integer comparison if both arguments are
integers, otherwise returns the result of a lexical comparison.
expr { +, − } expr
Addition or subtraction of integer-valued arguments.
expr { *, /, % } expr
Multiplication, division, or remainder of the integer-valued argu‐
ments.
expr : expr
The matching operator : (colon) compares the first argument with
the second argument which must be a regular expression. Regular
expression syntax is the same as that of ed(1), except that all
patterns are "anchored" (that is, begin with ^) and, therefore, ^
is not a special character, in that context. Normally, the match‐
ing operator returns the number of bytes matched (0 on failure).
Alternatively, the (...) pattern symbols can be used to return a
portion of the first argument.
EXAMPLES
Example 1: Incrementing a variable
Add 1 to the variable a:
example% fmlexpr $a + 1 | set -l a
Example 2: Setting a variable equal to a filename
For $a equal to either /usr/abc/file or just file:
example% fmlexpr $a : .*/\(.*\) \| $a
returns the last segment of a path name (that is, file). Watch out for
/ alone as an argument: fmlexpr will take it as the division operator
(see NOTES below).
Example 3: A better representation of Example 2
example% fmlexpr //$a : .*/\(.*\)
The addition of the // characters eliminates any ambiguity about the
division operator (because it makes it impossible for the left-hand
expression to be interpreted as the division operator), and simplifies
the whole expression.
Example 4: Counting characters in a variable
Return the number of characters in $VAR:
example% fmlexpr $VAR : .*
EXIT STATUS
As a side effect of expression evaluation, fmlexpr returns the follow‐
ing exit values:
0 if the expression is neither NULL nor 0 (that is, TRUE)
1 if the expression is NULL or 0 (that is, FALSE)
2 for invalid expressions (that is, FALSE).
ATTRIBUTES
See attributes(5) for descriptions of the following attributes:
┌─────────────────────────────┬─────────────────────────────┐
│ ATTRIBUTE TYPE │ ATTRIBUTE VALUE │
├─────────────────────────────┼─────────────────────────────┤
│Availability │SUNWcsu │
└─────────────────────────────┴─────────────────────────────┘
SEE ALSOed(1), expr(1), set(1F), sh(1), attributes(5)DIAGNOSTICS
syntax error for operator/operand errors
non-numeric argument if arithmetic is attempted on such a string
In the case of syntax errors and non-numeric arguments, an error mes‐
sage will be printed at the current cursor position. Use refresh to
redraw the screen.
NOTES
After argument processing by FMLI, fmlexpr cannot tell the difference
between an operator and an operand except by the value. If $a is an =,
the command:
example% fmlexpr $a = =
looks like:
example% fmlexpr = = =
as the arguments are passed to fmlexpr (and they will all be taken as
the = operator). The following works, and returns TRUE:
example% fmlexpr X$a = X=
SunOS 5.10 5 Jul 1990 fmlexpr(1F)
