C/Tcl Interface: Using UNIX commands

This page describes some UNIX commands that have been implemented in C such that there is no need to use exec 'command' any more. If you use the name of the command it will be executed directly. The implementations are very simple and cover only the most frequently used basic version of their corresponding UNIX counterparts. If you need a not covered functionality then you will have to use exec 'command' which will use the corresponding UNIX version.

All the commands use the standard command line parsing function and can thus be called with a -help argument.

You are encouraged to use the C implemented commands and avoid using UNIX commands because not all UNIX operating systems have the intelligence to organize their swap pages with a copy-on-write strategy.

All filename-using commands (except touch) do wild-card-expansion, and accept lists of filenames. Touch is a bit complicated, so if you need to touch wild-cards use the glob procedure of Tcl.

All commands catch the system-reported error messages if anything goes wrong, these are converted into Janus error messages and are returned as the command's result.

All commands will run without asking any questions. They are completely non-interactive.

rm <fileNames>
remove the named files
mv <from> <to>
move the file(s) in the from list (one argument, so pack multiple files in a list) to the file <to>, whcih must be a directory if <from> contains more than one element. (Directories can be moved, too.)
cd <directoryName>
change the current working directory to the given <directoryName>. All filenames that don't start with a slash will be treated relative to <directoryName>.
cp <from> <to>
copy the file(s) in the from list (one argument, so pack multiple files in a list) to the file <to>, which must be a directory if <from> contains more than one element. (Directories can be moved, too.)
sleep <time>
set the process asleep for <time>; seconds.
NOTE: The sleeping can not be interrupted.
wait <filename> [-intervall <i>] [-maxtime <max>]
set the process asleep until the file <filename> becomes readable (usually this means 'starts to exist'). Look for the file every <i> seconds, but not longer than <max> seconds. When the file becomes readable a value of "1" is returned, if the maximal time runs out without the file becoming readable a value of "0" is returned.
NOTE: Janus can not be interrupted while waiting for the file.
mkdir <directoryName> [-mode <mode>]
create the named directory. The default permission flags are set to 0755, if you want something else you can specify that in the <mode> parameter.
NOTE: for some reason, the mode flag is ignored by the system.
rmdir <directoryName>
remove the named directory (only if it is empty).
touch <fileName>
touch the named files, i.e. make their last-modified-times to be the current time. Create the files, if they don't exist.
NOTE: touch does not expand wild cards. Special characters are treated litteraly. This is because touch does not want to make assumptions about what is a special character and glob will return empty strings for nonexisting files, so the command touch *.x will create a file that is named "*.x". If you want to touch all *.x files do a touch [glob *.x].
date
has no arguments, return a human readable date string.