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

Table 27. Shell Operators (sh command) (continued)
Unary Operators
Additive Operators
+ − Addition, subtraction
Bitwise Shift Operators
> Bitwise shift right, bitwise shift left
Relational Operators
< > Less than, greater than
= Less than or equal, greater than or equal
= = != Equal to, not equal to
Bitwise AND/OR Operators
& AND
^ Exclusive OR
| Inclusive OR
Logical AND/OR Operators
&& Logical AND
|| Logical OR
? : If-else
Assignment Operator
= *= /= %=
+= −= = &= ^= |=
Assignment
You do not need the $(( )) syntax to enclose an arithmetic expression in these
situations:
v In assignment to an integer variable. (See typeset.)
v As an argument to the following built-in shell commands:
break exit return continue let shift
v When used as arguments in the test built-in shell command numeric
comparisons (–eq, –ge, –gt, –le, –lt, and –ne). See test.
Command Substitution
In command substitution, sh uses the expansion of the standard output of one
command in the command line for a second command. There are two syntaxes.
The first syntax (called backquoting)surrounds a command with grave accents `, as
in:
ls `cat list`
To process this command line, sh first runs the cat command and collects its
standard output. The shell then breaks this output into arguments and puts the
result into the command line of the ls command. The previous command therefore
lists the attributes of all files, the names of which are contained in the file list.
This syntax is easy to type, but is not useful if you want to put one command
substitution inside another (nesting command substitutions). A more useful syntax
is:
sh
Chapter 2. Shell command descriptions 563