guncat(1)

guncat - unencrypting file concatenation
(guncat_1.02.00.tar.gz)

2014-2018

NAME

guncat - catenates files, unencrypting pgp encrypted sections

SYNOPSIS

guncat [OPTIONS] [file(s)]
[OPTIONS] - cf. section OPTIONS
[file(s)] - optional files to process (cf. section INPUT FILE(S))

DESCRIPTION

Guncat was designed to tackle a problem encountered with (partically) PGP encrypted files (which may be encountered in, e.g., mailboxes). Tools to process text-files (like grep(1), or less(1)) may be used to process those files, but standard tools like cat(1) leave PGP encrypted sections within such files as-is. As a consequence, browsing the `real' contents (i.e., clear-text sections and the unencrypted contents of PGP encrypted sections) of those files is difficult.

Guncat acts comparably to cat, but unencrypts encrypted sections encountered in the files processed by guncat, copying the unencrypted information to guncat's standard output stream, which may thereupon be processed by other tools.

PGP/GPG encrypted sections are surrounded by


-----BEGIN PGP MESSAGE-----

and

-----END PGP MESSAGE-----

markers. Whenever guncat encounters such sections they will be processed by gpg(1). Gpg needs a passphrase to unencrypt such sections. The required passphrase may be provided to guncat, which then forwards the passphrase to gpg.

When providing an incorrect passphrase to guncat two additional attempts to provide the correct passphrase are provided. If the third attempt also fails, guncat terminates. Furthermore, when an incorrect passphrase is provided, the currently processed file must be reset to the beginning of the encrypted section. This implies that the processed file must be seekable. If the file does not support seeking operations then guncat also terminates.

RETURN VALUE

Guncat returns 0 to the operating system unless an error occurs (0 is also returned when the option --show-gpg) is specified.

INPUT FILE(S)

When no file arguments are provided (or when - is provided) the standard input stream is processed.

When option --passphrase is specified the first line of the first file that is processed is read as the passphrase to use. When a thus specified passphrase is incorrect, guncat terminates.

Any other argument is considered a file (path specifications are allowed) to be processed in sequence by guncat.

If an argument does not refer to a readable file, guncat terminates with an error message.

OPTIONS

Where available, single letter options are listed between parentheses following their associated long-option variants. Single letter options require arguments if their associated long options require arguments as well.

SEE ALSO

cat(1), gpg(1), grep(1), less(1).

BUGS

None reported

COPYRIGHT

This is free software, distributed under the terms of the `GNU General Public License'. Copyright remains with the author. Guncat is available at https://fbb-git.gitlab.io/guncat/

ORGANIZATION

Center for Information Technology, University of Groningen.

AUTHOR

Frank B. Brokken (f.b.brokken@rug.nl).