comb(1)

NAME

comb − combine SCCS deltas

SYNOPSIS

comb [-p sid] [-c list] [-o] [-s] file ...

DESCRIPTION

comb generates a shell procedure (see sh(1)) which, when run, reconstructs the given SCCS files. The reconstructed files are usually smaller than the original files. Arguments can be specified in any order, but all options apply to all named SCCS files. If a directory is named, comb behaves as though each file in the directory were specified as a named file, except that non- SCCS files (last component of the path name does not begin with s.) and unreadable files 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; non- SCCS files and unreadable files are silently ignored. The generated shell procedure is written on the standard output.

Options

comb recognizes the following options. Each is explained as if only one named file is to be processed, but the effects of any option apply independently to each named file.

-pSID The SCCS IDentification string (SID) of the oldest delta to be preserved. All older deltas are discarded in the reconstructed file.

-clist A list of deltas to be preserved (see get(1) for the syntax of a list). All other deltas are discarded.

-o For each get -e generated, this option 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 option can decrease the size of the reconstructed SCCS file. It can also alter the shape of the delta tree of the original file.

-s This option causes comb to generate a shell procedure which, when run, produces a report giving, for each file: 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 this option be used before any SCCS files are actually combined to determine exactly how much space is saved by the combining process.

If no options are specified, comb preserves only leaf deltas and the minimal number of ancestors needed to preserve the tree.

EXTERNAL INFLUENCES

International Code Set Support

Single- and multi-byte character code sets are supported.

DIAGNOSTICS

Use help(1) for explanations.

EXAMPLES

The command:

comb -c1.1,1.3,1.6 s.document > save_file

creates a shell script named save_file, which if executed, creates a new s.document using only the deltas 1.1, 1.3,and 1.6 from the old s.document. The script overwrites the old s.document; thus, it might be wise to copy the original elsewhere. Here is an example of typical technique:

cp s.document s.save
comb -c1.1,1.3,1.6 s.document > save_file
sh save_file

WARNINGS

comb may rearrange the shape of the tree of deltas. Combining files may or may not save space; in fact, it is possible for the reconstructed file to actually be larger than the original.

FILES

s.COMB????? Temporary file

comb????? Temporary file

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