fmlexpr(1F) fmlexpr(1F)
NAME
fmlexpr - evaluate arguments as an expression
SYNOPSIS
fmlexpr 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 0 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 precedence, with equal precedence operators grouped
within {} symbols.
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 arguments.
expr : expr
The matching operator : 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),
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fmlexpr(1F) fmlexpr(1F)
except that all patterns are ``anchored'' (that is, begin
with ^) and, therefore, ^ is not a special character, in
that context. Normally, the matching 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
1. Add 1 to the variable a:
`fmlexpr $a + 1 | set -l a`
2. For $a equal to either ``/usr/abc/file'' or just
``file'':
fmlexpr $a : .*/\(.*\) \| $a
returns the last segment of a path name (for example,
file). Watch out for / alone as an argument: fmlexpr
will take it as the division operator (see NOTICES
below).
3. A better representation of example 2.
fmlexpr //$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.
4. Return the number of characters in $VAR.
fmlexpr $VAR : .*
DIAGNOSTICS
As a side effect of expression evaluation, fmlexpr returns the
following 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).
syntax error for operator/operand errors
non-numeric argument
if arithmetic is attempted on such a string
Copyright 1994 Novell, Inc. Page 2
fmlexpr(1F) fmlexpr(1F)
In the case of syntax errors and non-numeric arguments, an
error message will be printed at the current cursor position.
Use refresh to redraw the screen.
NOTICES
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:
fmlexpr $a = =
looks like:
fmlexpr = = =
as the arguments are passed to fmlexpr (and they will all be
taken as the = operator). The following works, and returns
TRUE:
fmlexpr X$a = X=
REFERENCES
ed(1), expr(1), set(1F), sh(1)
Copyright 1994 Novell, Inc. Page 3