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Top Forums Shell Programming and Scripting Double square brackets question Post 302359803 by King Nothing on Wednesday 7th of October 2009 11:47:10 AM
Old 10-07-2009
Double square brackets question

Hi,
I just came across an interesting shell script syntax like the one below:
Code:
[[ $mode =  "INTERACTIVE" ]] && (trap 'rm -rf ${WORK_DIR}/*.$$; echo "\n\nInterrupted !!\n\n"; exit 4' 1 2 3 15)

Can someone please explain the code snippet above?
The trap command bit is fine but [[ $mode = "INTERACTIVE" ]] && is the hazy part.
Generally we use an if before [[ ]], but it is not being used here!

I was also experimenting with the below code snippet and it seemed to work fine as long as I was not putting #! /usr/bin/ksh at the top of the script.
Code:
[[ `ps -ef | grep Hawkmoon | grep -v grep` ]]

Why is it that it is running sans #! /usr/bin/ksh only?
I am using Solaris 5.8 by the way.
Thanks in advance Smilie.

Last edited by King Nothing; 10-07-2009 at 01:16 PM..
 

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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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