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Top Forums Shell Programming and Scripting Processing a file list via named pipe Post 302809079 by Scrutinizer on Saturday 18th of May 2013 07:09:28 AM
Old 05-18-2013
Usually named pipes would be used between two processes. The problem I see with this approach is that named pipes are byte oriented. So while you are writing the line oriented file list to the named pipe, the processes will be snatching the bytes off the named pipe and once it is gone, it is gone.

So in other words, those parallel reading processes would garble those file names, and so you would need to use some kind of signaling to synchronize the read operations so that it can only be performed by one process at the time..

Another approach might be to use one named pipe per reading process.
 

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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]... ksh93 print [-Renprs] [-f format] [-u fd] [string...] DESCRIPTION
ksh The shell output mechanism. When no options are specified, or when an option followed by ' a - is specified, or when just - is specified, the arguments are printed on standard output as described by echo(1). ksh93 By default, print writes each string operand to standard output and appends a NEWLINE character. Unless, the -r, -R, or -f option is speciifed, each character in each string operand is processed specially as follows: a Alert character.  Backspace character. c Terminate output without appending NEWLINE. The remaining string operands are ignored. E Escape character (ASCII octal 033). f FORM FEED character. NEWLINE character. Tab character. v Vertical tab character. \ Backslash character. x The 8-bit character whose ASCII code is the 1-, 2-, or 3-digit octal number x. OPTIONS
ksh The following options are supported by ksh: -n Suppresses new-line from being added to the output. -r-R Raw mode. Ignore the escape conventions of echo. The -R option prints all subsequent arguments and options other than -n. -p Cause the arguments to be written onto the pipe of the process spawned with |& instead of standard output. -s Cause the arguments to be written onto the history file instead of standard output. -u [ n ] Specify a one digit file descriptor unit number n on which the output is placed. The default is 1. ksh93 The following options are supported by ksh93: -e Unless -f is specified, process sequences in each string operand as described above. This is the default behavior. If both -e and -r are specified, the last one specified is the one that is used. -f format Write the string arguments using the format string format and do not append a NEWLINE. See printf(1) for details on how to specify format. When the -f option is specified and there are more string operands than format specifiers, the format string is reprocessed from the beginning. If there are fewer string operands than format specifiers, then outputting ends at the first unneeded for- mat specifier. -n Do not append a NEWLINE character to the output. -p Write to the current co-process instead of standard output. -r Do not process sequences in each string operand as described above. -R If both -e and -r are specified, the last one specified is the one that is used. -s Write the output as an entry in the shell history file instead of standard output. -u fd Write to file descriptor number fd instead of standard output. The default value is 1. EXIT STATUS
The following exit values are returned: 0 Successful completion. >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), ksh93(1), printf(1), attributes(5) SunOS 5.11 27 Mar 2008 print(1)
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