Owner's manual

Table 1 Selected OSS Shell Features (continued)
DescriptionFeature
A feature that allows user-assigned values to be passed to the shell and to variables
in the command line.
Parameter substitution
A feature that allows you to use a command’s output as if it was the value of a
variable.
Command substitution
Mechanisms for trapping interruptions and other OSS signals.Signal trapping
A feature that allows values, attributes, and comparisons to be tested.Conditional expressions
A feature that allows you to run, monitor, and manage foreground and background
processes.
Job control
The ability to group data and call it by a name.Arrays
Metacharacters
Table 2 lists shell metacharacters (characters that have special meaning to the shell).
Table 2 Shell Metacharacters
DescriptionMetacharacter
Syntactic
Separates commands that are part of a pipeline.|
Runs the next command if the current command succeeds.&&
Runs the next command if the current command fails.||
Separates commands that should be executed sequentially.;
Separates elements of a case construct.;;
Runs commands in the background.&
Groups commands to run as a separate process in a subshell.( )
Groups commands without creating a subshell.{ }
Filename
Separates the parts of a file’s pathname./
Matches any single character except a leading dot.?
Matches any sequence of characters except a leading dot.*
Matches any of the enclosed characters.[ ]
Specifies a home directory when used at the beginning of a filename.~
Quotation
Specifies that the following character should be interpreted literally; that is, without its
special meaning to the shell.
\
Specifies that any of the enclosed characters (except for the single-quotation-mark
character) should be interpreted literally; that is, without their special meaning to the
shell.
'...'
Specifies that the $ (dollar sign), ` (grave accent), and \ (backslash) characters keep
their special meaning to the shell, while all other enclosed characters should be
interpreted literally to the shell; that is, without their special meaning to the shell.
"..."
Input/Output
Redirects input.<
32 The OSS Shell