TCX

Section: User Commands (1)
Updated: 19 March 1993
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NAME

tcx - Transparantly compress executables

SYNOPSIS

tcx filename

DESCRIPTION

Tcx will replace an executable with a compressed version of it that is still capable of being executed. The amount of savings will depend on the compression algorithm configured for use by tcx. An executable compressed with tcx can be run as per normal with (hopefully) no side effects other than a minor delay in startup time.

Executables local to the system (not NFS mounted) are uncompressed in place and recompressed again some time after it stops being used. The standard timeout is 1/2 an hour.

Executables residing on NFS mounted directores are unpacked to a directory local to the system and run from there. These executables lie around for about one minute after disuse, after which time they get deleted.

All this action is transparant to the user, but executables residing on NFS mounted filesystems actually get the benefit of not hanging, in the event of paging activity, if the NFS server on which they live goes down. This fact will also improve the performance of executables on machines short of memory.

CAVEATS

Tcx will try to maintain permissions but in order to allow execution of a program on an NFS mounted filesystem to which another machine may not have root access to, it also sets the read bits on the executable corresponding to the execute bits. This may be a slight security flaw and if it causes you problems on particular executables, do not use it on them.

NFS mounted shell scripts which rely on `dirname $0` being set to something meaningful will probably break, as the TCX system can't fool the shell with a dummy argv[0] through the exec() call.

Tcx requires the corresponding untcx(1) program to be available otherwise transparency is not assured. Yell at your Systems Programmer if tcx'ed executables fail to execute.

BUGS

Tcx is still in beta test stage, so there are bound to be some. Please report any bugs or "patch"-style bug fixes (or new system ports) or even just suggested improvements, via email to slf@cs.mu.OZ.AU

AUTHOR

Stewart Forster, University Of Melbourne, 1993

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Time: 06:27:50 GMT, December 12, 2024

TCX