Writing to sequential file

[George James]

Does anyone know how to create a sequential file without getting a linefeed at the end?

If I create a file using stream or variable format and write some data to it then I get an unwanted linefeed character at the end.

For example:
GTM>set file="myFile.dat"
GTM>open file:(NEW:STREAM:NOWRAP)
GTM>use file write "abc"
GTM>close file
GTM>zsystem ls -al myFile.dat
GTM>zsystem "ls -al myFile.dat"
-rw-rw-r--   1 aussen  alster         4 Aug 25 21:48 myFile.dat
Although I have only written 3 characters to the file the file length is 4.  The last character is a linefeed $c(10) which I don't want.

This may be a bug, but from what I can tell from the docs it may be by design.  Whatever, I want to create a file that is not terminated by a linefeed.

Does anyone know a way of doing this?
Thanks.

[Dr. Martin Lehr]

Hi George,

some times ago I had to deal with the same problem.
It seems to be not a bug, because stream files in UNIX are delimited and GT.M does not
leave an undelimited record at the end of the file and adds an extra $C(10).

So, how to create a file without $C(10) at the end of the file?
I found the following (one can say, ugly) solution:

S F="test.dat"
O F:(NEWVERSION:WRAP:FIXED:RECORDSIZE=1:BLOCKSIZE=1):1 I '$T Q
U F
W "abc"
C F
ZSY "ls -al test.dat"
Q

This works with GTM 4.2-002. I don't know if it works with
GTM 4.3, I have not yet tested it. Disadvantage:
you have to replace constructions like W "abcde",!
with W "abcde",$C(10)

By the way: It is the Close that adds the extra $C(10).
So it is also possible to do the following:

S F="test.dat"
O F:(NEWVERSION:STREAM:NOWRAP):1 I '$T Q
W "abc"
ZSY "cp test.dat test1.dat"
C F
ZSY "ls -al test1.dat"
Q

Regards,
Martin

[George James]

Martin
Thank you.

I think I prefer the FIXED:BLOCKSIZE=1:RECORDSIZE=1:WRAP approach rather than renaming just before it is closed.

It would be nice to have a more intuitive Open argument that does this.

I can confirm that this does work on GTM 4.3-001B.

Regards
George

[John Murray]

Try issuing the following command just before you CLOSE file:

SET $X=0

That should fool GT.M into thinking there's no need to add the final line-terminator when you CLOSE the file.

John

[Dr. Martin Lehr]

Hi John,

I just tried out $X=0 before close -
it works perfectly!

I also must say that the BLOCKSIZE=1 - trick results in slow performance on floppy disks when the floppy is set to sync in fstab

So the $X=0 before close should be the better
solution

Thanks
Martin

[Sid]

I think there's another similar issue when writing to sequential files:

Try this code:

GTM>S file="myFile.dat"
GTM>O file:(NEW:STREAM:NOWRAP)
GTM>U file W "abc",#
GTM>C file
GTM>ZSYS "ls -l myFile.dat"
-rw-rw-rw- 1 sid dba 6 Mar 13 12:43 myFile.dat

As you can see, the length is 6 instead of 4 as expected. When I take a look at the content, I get "abc" + $C(10,12,10). GT.M wraps the FormFeed character $C(12) with 2 LineFeeds $C(10).
I noticed that if I change th Write statement to W "abc",*12 it does the job and adds only the $C(12) as expected.
If I change the Open parameters to NEW:WRAP:FIXED:RECORDSIZE=1:BLOCKSIZE=1
and let the Write statement as before: W "abc",# it works fine as well, but using these paremeters in large file coud slower performance.

Is there a better way to avoid the $C(10) characters without changing the original code W "abc",#  ?