z/OS V1R9.0 UNIX System Services Command ... - Christian Grothoff

sh
${parameter:+word}
Expands to word, provided that parameter is defined and non-empty.
${parameter+word}
Expands to word, provided that parameter is defined.
${parameter#pattern}
Attempts to match pattern against the value of the specified parameter. The
pattern is the same as a case pattern. sh searches for the shortest prefix of
the value of parameter that matches pattern. If sh finds no match, the
previous construct expands to the value of parameter; otherwise, the
portion of the value that matched pattern is deleted from the expansion.
${parameter##pattern}
Is similar to the preceding construct, except that sh deletes the longest part
that matches pattern if it finds such a match.
${parameter%pattern}
Searches for the shortest suffix of the value of parameter matching pattern
and deletes the matching string from the expansion.
${parameter%%pattern}
Is similar to the preceding construct, except that sh deletes the longest part
that matches pattern if it finds such a match.
Arithmetic Substitution
Arithmetic substitution is available with the syntax:
$((arithmetic expression))
or:
$[arithmetic expression]
This sequence is replaced with the value of arithmetic expression. Arithmetic
expressions consist of expanded variables, numeric constants, and operators.
Numeric constants have the forms:
v A number that starts with 0x is hexadecimal
v A number that starts with 0 is octal
v A number that does not start with 0x or 0 is decimal
v base #number, where base is a decimal integer between 2 and 36 inclusive, and
number is any nonnegative number in the given base.
Undefined variables evaluate to zero.
The operators are listed in decreasing order of precedence in Table 27. Operators
sharing a heading have the same precedence. Evaluation within a precedence
group is from left to right, except for the assignment operator, which evaluates from
right to left.
Table 27. Shell Operators (sh command)
Unary Operators
− Unary minus
! Logical negation
+ ~ Identity, bitwise negation
Multiplicative Operators
* / % Multiplication, division, remainder
562 z/OS V1R9.0 UNIX System Services Command Reference