SUMMARY: ksh limits on Alpha

[Chad Price <cprice@xxxxxxxxxxxxxxx>]

I got some very good answers, and 1 truely authoritative answer.

My question: (basically reaching the limits to the number of arguments 
allowable - how to find what the limit is...)

 > I've got a program which needs to provide a comparison value for
 > 95+94+...+1 data sets, and each comparison value comes out of another
 > program as a single file. Thus I'm creating large numbers of files as
 > output and running it under ksh.
 >
 > The process: I provide a file of file names (DNA sequences). My
 > home-written program reads the file of sequences, and then creates a shell
 > script which calls other programs to compare each sequence against every
 > other sequence. Each comparison creates a new output file (and this cannot
 > be changed - I have no source for the comparison program.)
 >
 > It's clear that 'ls' alone has no problem with just listing all the files,
 > but as soon as I use a wildcard to pick and choose among the output, I get
 > error messages about too many files.
 >
 > So: does anyone know what the limits are?  How many files? (it seems to be
 > larger than 2900 and smaller that 8100?) I can rewrite the part of the
 > analysis I do in order to create subdirectories for each X files, if I know
 > what value I should use for X.


Best (and most authoritative answer (from David Korn...))

 >You didn't say what OS the Alpha was running?  Are you running
 >NT or UNIX?

[ I'm using Unix... Tru64 4.0F ]

 >The limit is not imposed by the shell, it is imposed by the
 >exec() family of system calls. Thus, you should be able to do
 >	echo *
 >but not
 >	/bin/echo *
 >
 >Anyway
 >	getconf ARG_MAX
 >should tell you the total number of bytes that exec can use for arguments
 >and environment combined.

Which on my system returns:
gsaf.unmc.edu> getconf ARG_MAX
38912
gsaf.unmc.edu>

( Aside - what an odd number.... 38912 bytes?? )

 >
 >The xargs command can be used to break the argument list into pieces
 >and process for a group of arguments.

xargs(1)                                                             xargs(1)

NAME

   xargs - Constructs argument lists and runs commands

SYNOPSIS

   xargs [-e[eofstr]] [-E eofstr] [-i[replstr]] [-I replstr] [-l[number]] [-L
   number] [-n[number]] [-ptrx] [-slength] [CommandString] [argument...]

   The xargs command constructs a command line by combining a command string,
   containing a command and its options or arguments, with additional argu-
   ments read from standard input.



Thanks to folks for answering my questions. Several others suggested xargs 
also, which I'd heard of, but never used before.

Contributors:
David Korn <dgk@xxxxxxxxxxxxxxxx>
"Raymond Donovan" <rad@xxxxxxxxxxxx>
Phil Farrell <farrell@xxxxxxxxxxxxxxxxxxx>
Cherie Willoughby <willough@xxxxxxxxxx>
Hans Ranke <Hans.Ranke@xxxxxxxxx>
Stan Horwitz <stan@xxxxxxxxxxxxxxxxxxxxx>



Chad
Chad Price
Systems Manager, Genetic Sequence Analysis Facility
University of Nebraska Medical Center
986495 Nebraska Medical Center
Omaha, NE 68506-6495
cprice@xxxxxxxxxxxxxxx
(402) 559-9527
(402) 559-4077 (FAX)