3/15/72 IF (I)
NAME if -- conditional command
SYNOPSIS if expr command [ arg ... ]
1
DESCRIPTION if evaluates the expression expr, and if its
value is true, executes the given command with
the given arguments.
The following primitives are used to construct
the expr:
-r file
true if the file exists and is readable.
-w file
true if the file exists and is writable
-c file
true if the file either exists and is
writable, or does not exist and is cre-
atable.
s1 = s2
true if the strings s1 and s2 are equal.
s1 != s2
true if the strings s1 and s2 are not
equal.
These primaries may be combined with the follow-
ing operators:
!
unary negation operator
-a
binary and operator
-o
binary or operator
( expr )
parentheses for grouping.
-a has higher precedence than -o. Notice that
all the operators and flags are separate argu-
ments to if and hence must be surrounded by
spaces.
FILES --
SEE ALSO sh(I)
DIAGNOSTICS "if error", if the expression has the wrong syn-
tax; "command not found."
BUGS "-c" always indicates the file is creatable, even
if it isn't.
OWNER dmr