SunOS man pages : fmlexpr (1)
FMLI Commands fmlexpr(1F)
NAME
fmlexpr  evaluate arguments as an expression
SYNOPSIS
fmlexpr arguments
DESCRIPTION
The fmlexpr function evaluates its arguments as an expres
sion. After evaluation, the result is written on the stan
dard 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. Integervalued arguments may be
preceded by a unary minus sign. Internally, integers are
treated as 32bit, 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.
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 integervalued arguments.
expr { *, /, % } expr
Multiplication, division, or remainder of the
integervalued arguments.
expr : expr
The matching operator : (colon) compares the first
argument with the second argument which must be a reg
ular 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. Nor
mally, the matching operator returns the number of
SunOS 5.8 Last change: 5 Jul 1990 1
FMLI Commands fmlexpr(1F)
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 lefthand expression to be interpreted as the divi
sion 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 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).
ATTRIBUTES
See attributes(5) for descriptions of the following attri
butes:
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FMLI Commands fmlexpr(1F)
____________________________________________________________
 ATTRIBUTE TYPE  ATTRIBUTE VALUE 
__________________________________________________________
 Availability  SUNWcsu 
__________________________________________________________
SEE ALSO
ed(1), expr(1), set(1F), sh(1), attributes(5)
DIAGNOSTICS
syntax error
for operator/operand errors
nonnumeric argument
if arithmetic is attempted on such a string
In the case of syntax errors and nonnumeric arguments, an
error message will be printed at the current cursor posi
tion. 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 5.8 Last change: 5 Jul 1990 3



