IF(I) 3/15/72 IF(I)





IF(I)                        3/15/72                        IF(I)







NAME

     if -  conditional command



SYNOPSIS

     if expr command [ arg ... ]



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



     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   following

     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 arguments to if and hence

     must be surrounded by spaces.  Notice also that  parentheses

     are meaningful to the Shell and must be escaped.



SEE ALSO

     sh(I)



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