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Top Forums Shell Programming and Scripting In ksh, how does an in-line child sub-process get its own PID? Post 302074863 by MichLab on Friday 26th of May 2006 12:48:06 PM
Old 05-26-2006
MySQL

Thanks for the insights.

I do find the behaviour borderline nuts presuming different rules for coercing variables.

An arguably valid definition I can think of as an alternate is that "$$" is by definition the initial shell's PID as opposed to the current process's PID, independent of sub-shells much like PPID is the parent of the initial shell regardless of being in a sub-shell or not. This is consistent with a few ksh man pages I dug up though not obvious.

It also seems to be consistent with a few experiments I tried with "eval" with a composite string that results in "$$" which would preclude the initial parsing of the (....)& from coercing a manifest $$ and that also produced the same result.

That ksh treats a subshell differently from a forked instance of ksh is consistent with other aspects of behaviour (e.g. variables need not be exported to be seen by a sub-shell) but it sure messes up the notion of using inline code vs external scripts in any consistent manner.

I will derive an alternative strategy (messing with ps -ef is not an option because my code needs to run under Solaris and Windows/MKS wherein ps differs due to the information about process parameters maintained by Windows).

Thanks again.
Michel
 

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print(1)							   User Commands							  print(1)

NAME
print - shell built-in function to output characters to the screen or window SYNOPSIS
ksh print [ -Rnprsu [n]] [arg...] DESCRIPTION
ksh The shell output mechanism. With no flags or with flag - or -, the arguments are printed on standard output as described by echo(1). OPTIONS
The following options are supported: -n suppresses new-line from being added to the output. -R -r (raw mode) ignore the escape conventions of echo. The -R option will print all subsequent arguments and options other than -n. -p causes the arguments to be written onto the pipe of the process spawned with |& instead of standard output. -s causes the arguments to be written onto the history file instead of standard output. -u [ n ] flag can be used to specify a one digit file descriptor unit number n on which the output will be placed. The default is 1. EXIT STATUS
The following exit values are returned: 0 Successful operation. >0 Output file is not open for writing. ATTRIBUTES
See attributes(5) for descriptions of the following attributes: +-----------------------------+-----------------------------+ | ATTRIBUTE TYPE | ATTRIBUTE VALUE | +-----------------------------+-----------------------------+ |Availability |SUNWcsu | +-----------------------------+-----------------------------+ SEE ALSO
echo(1), ksh(1), attributes(5) SunOS 5.10 15 Apr 1994 print(1)
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