AT&T UNIX™PC Unix System V Users Manual - tenox

KSH ( 1 ) KSH(l)
The value of a named parameter may also be assigned by writing:
name= value [ name= value ] •••
If the integer attribute, -i, is set for name , the value is subject to
arithmetic evaluation as described below. Positional parameters,
parameters denoted by a number, may be assigned values with the
set special command. Parameter $0 is set from argument zero
when the Korn Shell is invoked. The character $ is used to introduce
substitutable parameters .
${parameter}
The value, if any, of the parameter is substituted. The
braces are required when parameter is followed by a
Jetter, digit, or underscore that is not to be interpreted as
part of its name or when a named parameter is subscripted.
If parameter is a digit then it is a positional
parameter. If parameter is * or @, then all the positional
parameters, starting with $1, are substituted (separated
by spaces). If an array identifier with subscript * or @ is
used, then the value for each of the elements is substituted
(separated by spaces).
${#parameter}
If parameter is not *, the length of the value of the
parameter is substituted. Otherwise, the number of positional
parameters is substituted.
${#identifier[*]}
The number of elements in the array identifier is substituted.
${parameter:-word}
If parameter is set and non-null then substitute its value;
otherwise substitute word .
${parameter :=word}
If parameter is not set or is null then set it to word; the
value of the parameter is then substituted. Positional
parameters may not be assigned to in this way.
${parameter:?word}
If parameter is set and is non-null then substitute its
value; otherwise, print word and exit from the shell. If
word is omitted then a standard message is printed.
${parameter:+word}
If parameter is set and is non-null then substitute word;
otherwise substitute nothing.
${parameter# pattern }
${parameter## pattern }
If the Korn Shell pattern matches the beginning of the
value of parameter, then the value of this substitution is
the value of the parameter with the matched portion
deleted; otherwise the value of this parameter is substituted.
- 5 -