Special variables

Special variables are internal variables provided by pBat. Special variables are local, thus they can not be inherited by external programs.

Special variable use

Special variables can not be modified, the can only be defined by pBat, the CALL command or the FOR command.

There is basically two types of special variables:

• Special variables prefixed by a single % (per cent) character which denotes a special variable reffering to an argument of the script.

• Special variables prefixed by two % characters which denote a special variable set within a loop by the FOR command.

Those two types of variables have a slightly different expansion precedence. Argument variables are expanded simultaneously with conventionnal expansion while FOR-generated variables are expanded before the delayed expansion and the tokenization of the command line.

Argument variables %0 through %9 are set to arguments passed to the script using the command line. As a convention, %0 is always the script name when the script starts. However, when using CALL to execute a label, %0 contain the name of that label.

The %* variable contains a line containing the parameters that have been passed to the script, that is it is the content of %1 trough %9 inside a single variable plus all the parameters beyond the ninth if any has been passed. The parameters beyond the ninth one (%9) can also be retrieved using the %+ variable. On UNIX-based operating systems, it is not possible to retrieve the exact syntax of the command line. Thus %* is created using the parameters and some added quotation if necessary.

Special variable expansion

Special variables names are made of a single letter or a digit. Any ASCII character except the 33 first (ie. from 0x20) can be used. However, for readability purposes it is better to use only letters.

Special variable expansion is performed between command argument detection and delayed expansion, allowing them to affect expansion of variables.

Special variable names need to be preceded by two %, (except for %0 up to %9, %* and %+) to be developed. Some option can be enabled by using the ~ sign. These options are the following:

• %%~I : Remove quotes around %%I.

• %%~fI : Expands to fully qualified path.

• %%~dI : Expands to %%I disk letter.

• %%~pI : Expands to %%I path.

• %%~nI : Expands to %%I file name.

• %%~xI : Expands to %%I file extension.

• %%~zI : Expands to %%I file size.

• %%~aI : Expands to %%I attributes.

• %%~tI : Expands to %%I access time.

Several options may be combined simultaneously (up to 16 different options).

As options are letters, conflicts can happen between variables names and options. If it is the case pBat will use the longest combination of options (maximum greediness). As an example, the following code :

ECHO %%~aI

Can be interpreted in two different ways:

• If %%I is defined, then %%~aI will be expanded.

• If %%I is not defined and %%a is, then %%~a will be expanded.

• Otherwise, no expansion takes place.

When the %0 variable gets expanded, pBat has a slightly different behaviour:

• if %0 or %~0 is specified, the variable will be replaced by the content of %0, stripped of its quote or not.

• if one ore more options is specified then the variable will be replaced by the effects of the options if they where processing the file name of the currently run batch. That is, %~f0 refers to the path of the script being executed, %~dp0 to its directory, and so on and so forth.

Note

Special variable names and options are case sensitive.

See also

Environment variables, Variable expansion, Specification index