A metacharacter is one of the following characters:
; & ( ) | < > new-line space tab
A blank is a tab or a space. An identifier is a sequence of letters, digits, or underscores starting with a letter or underscore. Identifiers are used as components of variable names. A vname is a sequence of one or more identifiers separated by a . and optionally preceded by a .. Vnames are used as function and variable names. A word is a sequence of characters from the character set defined by the current locale, excluding non-quoted metacharacters.
A command is a sequence of characters in the syntax of the shell language. The shell reads each command and carries out the desired action either directly or by invoking separate utilities. ...