ecFlow makes heavy use of different kinds of variables. There are several kinds of variables:

• Environment variables which are set in the UNIX shell before the ECFLOW-programs start. These control the server, and client (CLI).
• Internal variables: suite definition variables. These control server, ecflowview and CLI.
• Generated variables: These are generated within the suite definition node tree during job creation and are available for use in the jobs file.

This chapter lists the generated and user defined variables which have special meaning for ecFlow itself.
In an ecFlow script, ecFlow variables are written as text enclosed by a pair of %-characters (the edit-character.) As in C-format strings, if there are two %-characters together they are concatenated to form a single %-character in the job-file. For example if you need to execute the UNIX date command "date +%d". For a job, you must enter it as "date +%%d" into the ecFlow file.
The default edit-character is defined when ecFlow is compiled. It is possible to configure the edit-character to be defined as a variable ECF_MICRO (see section 3.6). The default installation uses the %-character.
You can define variables in a suite definition file using the edit keyword. User defined variables can occur at any node level: suite, family or task. ecFlow also generates variables from the node name, the host on which ecFlow is running, the time, the date and so on.