Looping through input/output Post: 302979883

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Top Forums UNIX for Beginners Questions & Answers Looping through input/output Post 302979883 by Don Cragun on Saturday 20th of August 2016 09:46:46 PM

08-20-2016

Registered User

I apologize for guessing wrong at what combining.executable does. I made the unwarranted assumption that a file named infile1 would be your 1st input file and that a file named infile2 would be your second input file instead of infile1 being the name of your 2nd input file and infile2 being the name of your 1st input file.

With that list of files and no indication of what produced it, I'll make another wild assumption that the list is the first couple of lines of output from the command:

Code:

ls *header

and that the intent is that your input files are to be processed in increasing alphanumeric sorted order. Assuming that is correct (which based on the failure of my earlier assumptions is certainly not guaranteed), the following will combine your input files and produce an output file named outfile. It uses temporary files named 0 and 1 and renames the last used temporary file to be outfile and removes the other temporary file before it exits:

Code:

#!/bin/ksh
i=0
last=0
for file in *header
do	case "$i" in
	(0)	f1=$file
		i=1
		;;
	(1)	combining.executable "$file" "$f1" > $((out = last))
		i=2
		;;
	(2)	out=$((1 - last))
		combining.executable "$file" $last > $out
		last=$out
		;;
	esac
done
mv $out "outfile"
rm -f $((1 - out))

Although written and tested using a Korn shell, this will work with any shell that uses basic Bourne shell syntax and supports POSIX arithmetic substitutions (such as ash, bash, dash, and ksh; but not csh and its derivatives, and not a traditional Bourne shell).

Don Cragun

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LEARN ABOUT ULTRIX

comb

comb(1) General Commands Manual comb(1)

Name
comb - combine delta versions of SCCS file

Syntax
comb [-o] [-s] [-psid] [-clist] files

Description
The command generates a shell procedure which, when run, will reconstruct the given SCCS files. For further information, see The recon-
structed files are generally smaller than the original files. The arguments may be specified in any order, but all keyletter arguments
apply to all named SCCS files. If a directory is named, behaves as though each file in the directory were specified as a named file,
except non-SCCS files (last component of the path name does not begin with s.) and unreadable files, which are silently ignored. If a
name of - is given, the standard input is read; each line of the standard input is taken to be the name of an SCCS file to be processed.

The generated shell procedure is written on the standard output.

Each keyletter argument is explained as though only one named file is to be processed, but the effects of any keyletter argument apply
independently to each named file.

Options
-clist Preserves specified deltas. See for the syntax of a list. All other deltas are discarded.

-o Causes the reconstructed file to be accessed at the release of the delta to be created. Otherwise the reconstructed file would
be accessed at the most recent ancestor. Use of the -o keyletter may decrease the size of the reconstructed SCCS file. It may
also alter the shape of the delta tree of the original file.

-pSID Indicates oldest delta to be preserved. All older deltas are discarded in the reconstructed file.

-s Generates a shell procedure which produces a report. This report gives the file name, size (in blocks) after combining, original
size (also in blocks), and percentage change computed by:
100 * (original - combined) / original
It is recommended that before any SCCS files are actually combined, one should use this option to determine exactly how much
space is saved by the combining process.

If no keyletter arguments are specified, will preserve only leaf deltas and the minimal number of ancestors needed to preserve the tree.

Restrictions
The command may rearrange the shape of the tree of deltas. It may not save any space; in fact, it is possible for the reconstructed file
to actually be larger than the original.

Diagnostics
See for explanations.

Files
s.COMB The name of the reconstructed SCCS file.
comb????? Temporary.
See Also
admin(1), delta(1), get(1), help(1), prs(1), sccs(1), sccsfile(5)
Guide to the Source Code Control System

comb(1)

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