# DO

> [HTML Version](do_lit.htm)

_Updated May 2022; see History_

**DO <fspec> <argument list>**

where _<argument list>_ is a list of zero or more space-delimited textual tokens which are bound to the formal [DO File Arguments](dofilearguments.htm.md) referenced within the file identified by _<fspec>_. 

The DO command forces _fspec_ to be treated as a command file rather than as a system command. This is useful in situations where the _fspec_ in question exists in .CMD and/or .LIT variations as well as .DO, since otherwise, the command search path would cause the .CMD or .LIT to be found first. It is also needed to force a file with an extension other than DO to be interpreted as a DO file—although it is not clear why you want to do that.

DO supports the command line argument _++fspec_; for details see [DO File Arguments](dofilearguments.htm.md). 

DO.LIT is invoked automatically by the command line processor if it determines that the specified file is a command (.CMD or .DO) file, so it is not necessary to explicitly use "DO" except in the situations described above. DO.LIT is responsible for preprocessing the DO file to perform argument and macro substitutions.

MDO.LIT is identical to DO.LIT, but is referenced internally under different circumstances.

**Comments**

The maximum DO file size is approximately 122K. This is about the maximum size for a 430K partition, which is about the minimum partition needed for some other large system commands, such as SUBMIT. A-Shell will explicitly complain if the partition size is not sufficient.

When DO is used within a command file to reference another command file, the command line may contain references variables input during execution of the current command file, \$KBD0 thru \$KBD9 (see [K0 - K9 Tokens](colon()tokens.htm.md)), may contain upper and lower case functions (see [Input Case](inputcase.htm.md)), and may use the concentration operator \$+ (see [Concatenate Parameters](concatenateparameters.htm.md)).

**History**

2022 May, A-Shell 6.5.1715, DO.LIT / MDO.LIT 2.1(126):  special colon commands (e.g. :K) can now be indented. Previously they needed to be in column one. This may be a minor detail but can make all the difference in debugging complex DO files with many levels of nested IF / ENDIF clauses.

2011 August, A-Shell 5.1.1227, DO.LIT / MDO.LIT 2.1(124) and SUBMIT.LIT 3.1(150) now support file-based variable command line arguments using the ++fspec syntax.