User guide

Table 12–2 (Cont.) Console Shell Operators
Operator Name Description
(),{} Grouping Shows which commands are grouped together in
complex command lines. These operators override
the [precedence] of pipe, sequence, and background
operators.
Form: {cmd1 ; cmd2} | cmd3
*,?,[...] Pattern specifiers Like OpenVMS wildcard characters. Used for matching
patterns in character strings.
* matches any character or characters or none
? matches any single character
[...] matches any of the enclosed characters
$string Environment vari-
able substitution
Treats the string as a legal environment variable and
translates it.
‘‘xxx’’ String with no
substitution
Passes the string without effect.
‘‘String’’ String with
substitution
Passes the string after expanding wildcards and
environment variables.
‘‘cmd’’ Command
substitution
Treats the string as a command, executes it, and
substitutes it in the resulting output.
12.1.4 Using Flow Control
The console uses the following reserved words: if, then, else, elif, fi, case, in,
esac, for, while, until, do, and done. These words provide a limited number
of flow control structures at the shell command level. The syntax for these
constructions is as follows:
• while command_sequence done
• while command_sequence do command_sequence done
• until command_sequence done
• until command_sequence do command_sequence done
• for name do command_sequence done
• for name in list do command_sequence done
• case word in case_part_list
pattern ) command_sequence ;;
[ pattern ) command_sequence ;; ]
esac
12–4 Console Primer