How to get unix command output in skill

Hi,

Try an ipcWaitForProcess(cid) before the Read.

Best regards,

Lawrence.

Thanks for quick response.

I tried but not working...

Really? It should work. The only alternative I might suggest is to try an asynchronous approach by setting up a data handler to receive the result from the IPC process.

Best regards,

Lawrence.

See what I did.

In my tt.il:

procedure(unixReturn()
let((cid scriptPath)
cid = ipcBeginProcess("which cp")
printf("cid is %s\n" cid)
ipcWaitForProcess(cid)
scriptPath = ipcReadProcess(cid)
printf("S path is %s\n" scriptPath )
);let
);prog

And I run in CIW:

1) Load the script and run the function, see the print result

\i load("~/tt.il")
\o function unixReturn redefined
\t t
\i unixReturn()
\o cid is ipc:61
\o S path is
\t t

2) Type in line by line with the tt.il into the CIW, now I can get the result:

\i cid = ipcBeginProcess("which cp")
\t ipc:62
\i ipcWaitForProcess(cid)
\t nil
\i scriptPath = ipcReadProcess(cid)
\t "/usr/bin/cp\n"
\i printf("S path is %s\n" scriptPath )
\o S path is /usr/bin/cp
\o
\t t

Anyone can help on this??

Ah yes, I encountered this same situation myself, once upon a time...  

It was a fun little puzzle to solve, but if you want to skip to the end of the mystery novel, here is the solution:

<SPOILERS>

Replace ipcWaitForProcess(cid) with ipcWait(cid).

</SPOILERS>

The reason it's not working from a script is because ipcWaitForProcess() only waits for the process to start up, so you're calling ipcReadProcess() before the process has actually had a chance to produce any output yet.  (Which is why it works from the CIW: in the time it takes you to type ipcReadProcess(cid), the process has finished.)  So in a script, if you want to guarantee that the process has done its thing and printed output for SKILL to read, you need to wait for it to finish, which is what ipcWait() does.  (Yes, I know they're not very good names.)

If you really want to use ipcWaitForProcess(), then you need to use a while() loop to keep reading and accumulating output text while ipcIsActiveProcess(cid).  

Note you can also pass a 2nd argument to ipcReadFromProcess(o_childId [x_timeOut]) which tells it to wait x seconds for the process to print something before giving up.

wenckey said:

I want to get some output like "which" for a script's real path in skill script.

I should also mention that SKILL has various `which'-like commands that can be used without having to resort to ipcBeginProcess(strcat("which " scriptName)).  E.g.,

simplifyFilename(
t_name
[ g_dontResolveLinks ]
)
=> t_result

Expands the name of a file to its full path.

simplifyFilenameUnique(
t_path
)
=> t_fullPath / error message

Returns the full path for the given t_path without links and
a trailing slash / at the end of the result string. The function
returns an error if the given t_path is incorrect.

SKILL novices often reach for ipc* functions to perform simple tasks for which there are already builtin functions (e.g. ipcBeginProcess("whoami") instead of getLogin()).

Really helpful!

Thanks a lot~