Using Edlin to Edit Files Too Large to Fit in Memory (81854)
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
This article was previously published under Q81854
Edlin can be used to edit files that are of any size. Using the write
(W) and append (A) commands within Edlin, you are able to load and
edit portions of a file one at a time (that is, load, edit, write to
disk, load another segment, edit, write to disk, and so on).
When you start Edlin in MS-DOS 5.0, it reads lines from your file
until memory is 75 percent full. (Many previous versions of MS-DOS
restrict the amount of the file that can be read to about 64K minus
the size of the Edlin program file.) To edit the remainder of the
file, you first have to write an equivalent amount of lines in memory
to disk and then load the rest of the file, as follows:
• Write a set amount of lines to the disk, using the W command. W
will write all of the current lines to disk, clearing them from the
memory buffer. Once written, the lines are no longer in memory to
modify. If you want to specify a certain number of lines to be
written, use "nW", where n is the amount of lines to be written
from memory to disk.
• Use the Append command to load the rest of the file [or as much as
can be read]. To specify a certain number of lines to be read,
specify "nA", where where n is the number of lines to be loaded
from disk to memory.
Repeat these two commands until you are finished editing the entire
• Whenever you write to the disk, it renumbers the lines of the
file that are in memory, starting with 1.
For example, writing 2 lines of a 10 line file from memory to disk:
Ten lines of the Write to disk Only eight lines of the
file in memory -> 2W -> file remain in memory
starting at 1.
1: @echo off 1: prompt $p$g
2: path=c:\dos 2: set temp=c:\dos
3: prompt $p$g ..
4: set temp=c:\dos ..
Specify the same number of lines that will be written to disk as
will be appended to memory. This way, you can keep track of where
you are in a file. (Try writing and appending 50 or 100 lines, for
example, 50W and 50A.)
After Edlin reads the last line of the file into memory, the
message "End of input file" is displayed. After editing that
portion, you can use the Exit command to exit Edlin and save the
rest of the file.
Remember that this process is one way, from the front to the end of
the file. To edit a portion that has already been written to disk,
you have to quit the session of Edlin and start from the beginning
When the MS-DOS 5.0 Editor is started using the EDIT command, it
occupies about 289K of RAM. The largest size file that can be edited
using Editor is about the largest executable program size (as reported
by MEM or CHKDSK) minus 289K. For more information on the largest
size file that Editor can modify, query on the following words in the
Microsoft Knowledge Base:
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