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Feature #1231

system command

Added by John Abbott over 5 years ago. Updated over 4 years ago.

Status:
Closed
Priority:
Normal
Assignee:
John Abbott
Category:
CoCoA-4 function to be added
Target version:
CoCoA-5.3.0
Start date:
26 Oct 2018
Due date:
% Done:

100%

Estimated time:
Spent time:
5.65 h

Description

CoCoA-4 had a system command which would pass its string argument to a shell for execution.

There is no such command in CoCoA-5 since it is obviously unsafe e.g. the string could be "cd; rm -rf *"

Martin says they need the system command for various interactions between ApCoCoA and other programs.

A possible approach might be to have a system command which is activated only if CoCoA is started with a suitable argument; so you have to start CoCoA in a "special" way to be able to use the system command.

Is this a reasonable compromise? Are there any other ideas?

Related issues

Related to CoCoA-5 - Support #1311: THINGS TO DO IN GENOVA September 2019Closed2019-09-11

Related to CoCoA-5 - Support #1222: Release CoCoA-5.3.0Closed2018-08-28

Related to CoCoA-5 - Bug #1502: SystemCommand in Microsoft versionIn Progress2020-10-08

Related to CoCoA-5 - Bug #1524: wrong SystemCommand exit valueClosed2020-10-28

History

#1 Updated by Anna Maria Bigatti over 5 years ago

  • % Done changed from 0 to 10

I believe that Macaulay and Singular have such a command, and they use it for their interfaces.
So I do agree that we should add it ourselves, and with an explicit flag.
Maybe we could also forbid the substring rm in system, and make a system_rm function, so it is easy to spot call to rm?

#2 Updated by John Abbott over 5 years ago

  • Status changed from New to In Progress

I have made a first attempt at implementing a "system call" function, but I am not really comprehending the structure of the interpreter :-(

I want there to be a "global" flag which is set at initial start up (and should never be changed thereafter), and then the interpreter should immediately give an error if someone attempts to execute a system command when this is not allowed by the "global" flag.

So far I have been copying blindly code used for the describe command, but that seems to have been a bad idea. Maybe return is better?

#3 Updated by John Abbott over 5 years ago

I am now thinking that making system a new interpreter command was not a clever idea. It can simply be a built-in function; this should be much easier to implement.

Note that there is no corresponding function to add to CoCoALib since the C++ standard function system is always available.

#4 Updated by John Abbott over 5 years ago

  • Status changed from In Progress to Resolved
  • Assignee set to John Abbott
  • % Done changed from 10 to 80

This seems to be (almost) done, but I cannot yet access CVS...

#5 Updated by John Abbott about 5 years ago

I repeat here something I wrote on "Telegram" (because redmine was down).

The name system causes a clash with an example from the CoCoAManual (where a top-level variable called system is used). Indeed, it seems natural for people to want to use the name system.

What should the name of the function for making "system calls" be?

Other possible choices are SystemCall or SysCall, SystemCommand or SystemCmd or SysCmd, perhaps also ShellCommand or CLICommand (but maybe this is Unix/Linux-specific?).

Note that Wikipedia makes a clear distinction between "system call" and "system command". In our case, only "system command" is correct.

My current preference is with SystemCmd (or perhaps SystemCommand); for some reason SysCmd seems too short/cryptic.

#6 Updated by Anna Maria Bigatti about 5 years ago

Note that Wikipedia makes a clear distinction between "system call" and "system command". In our case, only "system command" is correct.

My current preference is with SystemCmd (or perhaps SystemCommand); for some reason SysCmd seems too short/cryptic.

I'll check the meaning, but I still think that SystemCall would be more self-explanatory.
Otherwise SystemCommand, with no abbreviations. Or, better, SystemCommand_Beware_AtYourRisk ;-)

#7 Updated by John Abbott about 5 years ago

OK, the longer name SystemCommand is clearer, and anyway the function should only very rarely be called, so succinctness is unimportant (and it is nice that the name is long enough to be easily visible.

#8 Updated by John Abbott over 4 years ago

There is currently no manual entry for SystemCommand.

#9 Updated by John Abbott over 4 years ago

  • Related to Support #1311: THINGS TO DO IN GENOVA September 2019 added

#10 Updated by John Abbott over 4 years ago

#11 Updated by John Abbott over 4 years ago

  • Status changed from Resolved to Feedback
  • % Done changed from 80 to 90

There is a manual page now.

#12 Updated by John Abbott over 4 years ago

Currently, any output from the system command is sent to stdout (so might be lost if a GUI is being used).
Perhaps it would be better to have the result being a record of the form record[ExitCode:=0, output:="abc"]

Comments, ideas, suggestions?
KISS?

#13 Updated by Anna Maria Bigatti over 4 years ago

  • Status changed from Feedback to Closed
  • % Done changed from 90 to 100

Tested on MacOSX.
Works.

#14 Updated by John Abbott over 3 years ago

  • Related to Bug #1502: SystemCommand in Microsoft version added

#15 Updated by John Abbott over 2 years ago

  • Related to Bug #1524: wrong SystemCommand exit value added

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