Re: Reading a line of arbitrary length

[Rex Reges <reges@mds.lmco.com>]

Ted Dennison wrote:
> 
> Hmmm. I thought all unix (and VMS) shells had a command-line limit of 256
> characters (or less). Is that not the case?
> 

Your observation is interesting for reasons other than the Get_Line 
problem.  Get_Line can apply to either a file or keyboard input.  The 
file input is where most problems occur. Files can have very
long lines (they end when the end-of-line character is 
encountered which is not necessary an end-of-record).

The problem with command line input on Unix is that it does 
require arbitrarily long string inputs.  For example, when
the command "grep -i find_me *" is issued, the asterisk 
must be replaced by the names of all of the files in the current
directory before the command is passed to grep.  

It happens frequently that you may want to search some source
code reference directory for with's or whatever.  For a medium
size job of 100,000 lines of code, this may involve 1000 file
names (package specs, package bodies, separates, etc.).  The 
file names tend to get long due to separates, maybe 30 characters
average length.  The string passed to grep ends up being over
30,000 characters long!  

Many Unix implementations cannot handle this problem and the 
grep fails.  Obviously with big jobs the problems get even worse.

Note that VMS does have a limit of 255 or so as you stated, but
you can tack on quite a few continuation lines.  Maybe the 
overall limit is 4095?

-- 
Rex Reges                      or you can call me The Fixer 
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Lockheed Martin, M&DS          or you can call me The Doctor
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