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Full Discussion: Help with executing awk and While loop
Top Forums Shell Programming and Scripting Help with executing awk and While loop Post 302782059 by Don Cragun on Monday 18th of March 2013 08:10:57 AM
Old 03-18-2013
OK. Let's analyze what is happening. We have a file named sample.txt containing:
Code:
Source Name: xxx
Department|Revenue
1001|3252
1002|3345

and we have a script (reformatted and line numbers added for discussion):
Code:
1  awk 'NR > 2' sample.txt |
2  while read Dep;
3  do awk -F '|' '{print $1}' ;
4  done

So, first, the awk on line 1 reads and discards the first two lines from sample.txt and writes the last two lines from sample.txt into the pipe feeding line 2.

The read on line 2 sets Dep to 1001|3252 (consuming the 3rd line from sample.txt that was the 1st line output by the awk on line 1).

Then (since no other input file is specified) the awk on line 3 reads the remainder of the output from the awk on line 1 and prints 1002.

Then the next call to read on line 2 hits EOF and terminates the while loop.

If you want the awk on line 3 to process the data stored in $Dep, you could change your script to something like:
Code:
awk 'NR > 2' sample.txt | while read Dep; do echo "Processing $Dep"; echo "$Dep" | awk -F '|' '{print $1}' ; done

Note the text in red that I've added to your script. This modified script produces the output:
Code:
Processing 1001|3252
1001
Processing 1002|3345
1002

I hope this helps,
Don
 

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LEARN ABOUT MOJAVE

platform::shell

platform::shell(n)					       Tcl Bundled Packages						platform::shell(n)

__________________________________________________________________________________________________________________________________________________

NAME

       platform::shell - System identification support code and utilities

SYNOPSIS

       package require platform::shell ?1.1.4?

       platform::shell::generic shell
       platform::shell::identify shell
       platform::shell::platform shell
_________________________________________________________________

DESCRIPTION

       The platform::shell package provides several utility commands useful for the identification of the architecture of a specific Tcl shell.

       This  package  allows the identification of the architecture of a specific Tcl shell different from the shell running the package. The only
       requirement is that the other shell (identified by its path), is actually executable on the current machine.

       While for most platform this means that the architecture of the interrogated shell is identical to the architecture of  the  running  shell
       this  is  not generally true. A counter example are all platforms which have 32 and 64 bit variants and where a 64bit system is able to run
       32bit code. For these running and interrogated shell may have different 32/64 bit settings and thus different identifiers.

       For applications like a code repository it is important to identify the architecture of the shell which will  actually  run  the  installed
       packages, versus the architecture of the shell running the repository software.

COMMANDS

       platform::shell::identify shell
	      This command does the same identification as platform::identify, for the specified Tcl shell, in contrast to the running shell.

       platform::shell::generic shell
	      This command does the same identification as platform::generic, for the specified Tcl shell, in contrast to the running shell.

       platform::shell::platform shell
	      This command returns the contents of tcl_platform(platform) for the specified Tcl shell.

KEYWORDS

       operating system, cpu architecture, platform, architecture

platform::shell 						       1.1.4							platform::shell(n)
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