Difference between revisions of "SPAWN"
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==Purpose== | ==Purpose== | ||
Execute an external program and optionally wait for its completion | Execute an external program and optionally wait for its completion | ||
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pid = spawnpid() | pid = spawnpid() | ||
on escape killed = cancelpid(pid) | on escape killed = cancelpid(pid) | ||
| − | if | + | if not activepid(pid) |
| − | set message to "Printing completed." | + | set message to "Printing completed." |
endif | endif | ||
</code> | </code> | ||
| Line 36: | Line 29: | ||
==Products== | ==Products== | ||
| − | Recital | + | Recital Server, Recital |
[[Category:Documentation]] | [[Category:Documentation]] | ||
[[Category:Commands]] | [[Category:Commands]] | ||
| + | [[Category:Disk and File Utilities]] | ||
| + | [[Category:Disk and File Utilities Commands]] | ||
Latest revision as of 16:04, 25 November 2009
Purpose
Execute an external program and optionally wait for its completion
Syntax
SPAWN | !! <os-command>
See Also
ACTIVEPID(), CANCELPID(), SPAWNPID()
Description
The SPAWN command is synonymous with the !! command. These commands provide the facility for executing external programs, in the 'background', from within the Recital/4GL. The SPAWN command differs from the RUN command in that the specified <os command> executes in parallel without waiting until command execution is complete. It is particularly useful for generating reports from shared tables. When running a command in the background, terminal output is disabled for the background command if it is running the Recital/4GL.
The SPAWNPID() function returns the identity of the spawned process. The ACTIVEPID(<pid>) function returns .T. if the specified process is still active and .F. otherwise. The CANCELPID(<pid>) function returns .T. if the specified process could be 'killed' and .F. otherwise. A spawned process will only remain active while the user remains logged in. All spawned processes will be terminated when the user logs out.
Example
spawn db printrep pid = spawnpid() on escape killed = cancelpid(pid) if not activepid(pid) set message to "Printing completed." endif
Products
Recital Server, Recital
