[ < ] | [ > ] | [ << ] | [ Up ] | [ >> ] | [Top] | [Contents] | [Index] | [ ? ] |
3.4.1 Positional Parameters The shell's command-line arguments. 3.4.2 Special Parameters Parameters with special meanings.
A parameter is an entity that stores values.
It can be a name
, a number, or one of the special characters
listed below.
For the shell's purposes, a variable is a parameter denoted by a
name
.
A variable has a value and zero or more attributes.
Attributes are assigned using the declare
builtin command
(see the description of the declare
builtin in 4.2 Bash Builtin Commands).
A parameter is set if it has been assigned a value. The null string is
a valid value. Once a variable is set, it may be unset only by using
the unset
builtin command.
A variable may be assigned to by a statement of the form
name=[value] |
integer
attribute set, then value
is subject to arithmetic expansion even if the $((...))
expansion is not used (see section 3.5.5 Arithmetic Expansion).
Word splitting is not performed, with the exception
of "$@"
as explained below.
Filename expansion is not performed.
Assignment statements may also appear as arguments to the
declare
, typeset
, export
, readonly
,
and local
builtin commands.