Maximum Line Length and Count for Batch Files & CONFIG.SYS (69563)
The information in this article applies to:
- Microsoft MS-DOS operating system 3.1
- Microsoft MS-DOS operating system 3.2
- Microsoft MS-DOS operating system 3.21
- Microsoft MS-DOS operating system 3.3
- Microsoft MS-DOS operating system 3.3a
- Microsoft MS-DOS operating system 4.0
- Microsoft MS-DOS operating system 4.01
- Microsoft MS-DOS operating system 5.0
- Microsoft MS-DOS operating system 5.0a
- Microsoft MS-DOS operating system 6.0
- Microsoft MS-DOS operating system 6.2
- Microsoft MS-DOS operating system 6.21
- Microsoft MS-DOS operating system 6.22
This article was previously published under Q69563 SUMMARY
This article contains information on the maximum number of lines and line
length allowed for batch files (including the AUTOEXEC.BAT file) and the
CONFIG.SYS file.
MORE INFORMATIONBatch Files
There is no apparent limit. A test batch file with 67,000 lines and a total
of 804,000 bytes ran all the way through (but it took 15 minutes to do so
on a 386/33 machine). COMMAND.COM reads one batch line at a time, and only
retains a file pointer for the batch file, so it does not require a large
buffer to hold batch file commands before processing them. This should
allow for batch files that span an entire disk, if so desired.
Each batch file line does have a limit, however. Any batch file line
exceeding 127 bytes is truncated at 127 bytes before it is processed.
CONFIG.SYS File
There is no limit on lines, but there is a 64-kilobyte (65,534 byte) limit
on the overall file size. A test with a CONFIG.SYS that contained only 76-
byte long REM statements (except for the last line, which loaded a device
driver) loaded properly. There do appear to be some problems on the
boundary condition when the CONFIG.SYS file size reaches 65,535 bytes.
Each CONFIG.SYS line does not appear to have a limit. The device driver
INIT code is given a pointer to a read-only buffer, which contains the
remainder of the CONFIG.SYS file, not just the command line. With this
pointer, you can access a command line of any length.
Modification Type: | Major | Last Reviewed: | 5/12/2003 |
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Keywords: | KB69563 |
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