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Top Forums Shell Programming and Scripting Background processes in a pipeline don't run asynchronously? Post 302561139 by ygemici on Monday 3rd of October 2011 09:04:57 AM
Old 10-03-2011
I think , in g() function , when ${1} fd goes to background ,f() function process at once,after then pipe is missing for that created 63fd..
therefore `/dev/fd/63` fd can not found by the g function.so g() function can not call f() function via same fd at the same time..
maybe you can try like this Smilie
Code:
..............
g() {
exec 4<${1}
f 1 <${1} &
f 2 <&4
}
...............
.........

regards
ygemici
 

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pid(n)                                                         Tcl Built-In Commands                                                        pid(n)

__________________________________________________________________________________________________________________________________________________

NAME
pid - Retrieve process identifiers SYNOPSIS
pid ?fileId? _________________________________________________________________ DESCRIPTION
If the fileId argument is given then it should normally refer to a process pipeline created with the open command. In this case the pid command will return a list whose elements are the process identifiers of all the processes in the pipeline, in order. The list will be empty if fileId refers to an open file that is not a process pipeline. If no fileId argument is given then pid returns the process identi- fier of the current process. All process identifiers are returned as decimal strings. EXAMPLE
Print process information about the processes in a pipeline using the SysV ps program before reading the output of that pipeline: set pipeline [open "| zcat somefile.gz | grep foobar | sort -u"] # Print process information exec ps -fp [pid $pipeline] >@stdout # Print a separator and then the output of the pipeline puts [string repeat - 70] puts [read $pipeline] close $pipeline SEE ALSO
exec(n), open(n) KEYWORDS
file, pipeline, process identifier Tcl 7.0 pid(n)
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