A syntax diagram shows how a command should be specified so that the operating system can correctly interpret what is typed.
Read a syntax diagram from left to right, and from top to bottom, following the horizontal line (the main path). If the line ends with an arrowhead, the command syntax is continued, and the next line starts with an arrowhead. A vertical bar marks the end of the command syntax.
When typing information from a syntax diagram, be sure to include punctuation, such as quotation marks and equal signs.
Parameters are classified as keywords or variables:
A parameter can be a combination of a keyword and a variable.
Required parameters are displayed on the main path:
>>-COMMAND-required parameter----------------------------------><
Optional parameters are displayed below the main path:
>>-COMMAND-+--------------------+------------------------------>< '-optional parameter-'
A parameter's default value is displayed above the path:
>>-COMMAND---+-----------------------+------------------------->< | .-VALUE1--. | '-OPTPARM--+-VALUE2--+--' +-VALUE3--+ '-VALUE4--'
A stack of parameters, with the first parameter displayed on the main path, indicates that one of the parameters must be selected:
>>-COMMAND---+-required choice1-+------------------------------>< '-required choice2-'
A stack of parameters, with the first parameter displayed below the main path, indicates that one of the parameters can be selected:
>>-COMMAND---+------------------+------------------------------>< +-optional_choice1-+ '-optional_choice2-'
An arrow returning to the left, above the path, indicates that items can be repeated in accordance with the following conventions:
.-------------------------. V | >>-COMMAND-------repeatable parameter---+----------------------><
.-,-----------------------. V | >>-COMMAND-------repeatable_parameter---+----------------------><
Items from parameter stacks can be repeated in accordance with the stack conventions for required and optional parameters discussed previously.
Some syntax diagrams contain parameter stacks within other parameter stacks. Items from stacks can only be repeated in accordance with the conventions discussed previously. That is, if an inner stack does not have a repeat arrow above it, but an outer stack does, only one parameter from the inner stack can be chosen and combined with any parameter from the outer stack, and that combination can be repeated. For example, the following diagram shows that one could combine parameter choice2a with parameter choice2, and then repeat that combination again (choice2 plus choice2a):
>>-COMMAND------------------------------------------------------> .---------------------------------------------------. V | >--------+------------------------+---parameter choice3---+---->< +-parameter choice1------+ +-parameter choice2------+ '-+--------------------+-' +-parameter choice2a-+ +-parameter choice2b-+ '-parameter choice2c-'
Some commands are preceded by an optional path parameter:
>>-+------+--COMMAND------------------------------------------->< '-path-'
If this parameter is not supplied, the system searches the current directory for the command. If it cannot find the command, the system continues searching for the command in all the directories on the paths listed in the .profile.
Some commands have syntactical variants that are functionally equivalent:
>>-+-COMMAND FORM1-+------------------------------------------->< '-COMMAND FORM2-'