A metacharacter is one of the following characters:
; & ( ) | < > space tab newline-character
A blank is either a tab or space. An identifier consists of a string of letters, digits and the underscore character _. This string must begin with a letter or underscore. Identifiers are used as names for functions and variables. A word is a string of characters which are separated by one or more metacharacters. Each of the metacharacters has a special meaning for the POSIX shell and is used as a word separator unless quoted.
Quote | Meaning |
| A metacharacter preceded by a backslash \ is quoted and therefore stands for itself. The pair \new-line-character is ignored or deleted by the POSIX shell. |
| All characters which are enclosed in apostrophes '...' are quoted. However, a pair of apostrophes may not enclose a single apostrophe. |
| Strings which are enclosed in quotes "..." are subject to parameter and command substitution. When accompanied by a backslash they can be used to quote the backslash \, backquote ` , quotation mark " and dollar sign $. $* and $@ mean the same thing provided that they are not enclosed in quotes or used as a file name or as a value for variable assignment. Their meanings differ if they are used alone in quotes or if they used as command arguments. "$*" corresponds to "$1 |
| Strings which are enclosed in backquotes `...` can be quoted by using the backslash \, backquotes ` and the dollar sign $. If the whole string needs to be enclosed in quotation marks "...`...` ..." you can use the backslash \ to quote the quotation mark ". |
The special meaning of reserved words or aliases can be removed by quoting any character of the reserved word. However, it is also sufficient to entire a single "\" before the name in order to quote the entire word (e.g. "\while").
The recognition of function names or built-in command names cannot be suppressed in this way.