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Shell Programming and Scripting
PERL: how to tell if variable is NULL
Post 34865 by oombera on Tuesday 18th of March 2003 02:03:07 PM
03-18-2003
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I have the necessity to use this command:
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The above command send a cat error.
Any idea?
Thanks.
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Hello
I want to check for NULL variable..
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hi forum
i beginning with script and i want test un null variable in a schell
i just don t know the syntax here is a litle example
y=test
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then
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Hi,
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LEARN ABOUT HPUX
rc.config
rc.config(4) Kernel Interfaces Manual rc.config(4) NAME
rc.config, rc.config.d - files containing system configuration information SYNOPSIS
DESCRIPTION
The system configuration used at startup is contained in files within the directory The file sources all of the files within and and exports their contents to the environment. /etc/rc.config The file is a script that sources all of the scripts, and also sources To read the configuration definitions, only this file need be sourced. This file is sourced by whenever it is run, such as when the command is run to transition between run states. Each file that exists in is sourced, without regard to which startup scripts are to be executed. /etc/rc.config.d The configuration information is structured as a directory of files, rather than as a single file containing the same information. This allows developers to create and manage their own configuration files here, without the complications of shared ownership and access of a common file. /etc/rc.config.d/* Files This is where files containing configuration variable assignments are located. Configuration scripts must be written to be read by the POSIX shell, and not the Bourne shell, or In some cases, these files must also be read and possibly modified by control scripts or the sam program. See sd(4) and sam(1M). For this reason, each variable definition must appear on a separate line, with the syntax: No trailing comments may appear on a variable definition line. Comment statements must be on separate lines, with the comment character in column one. This example shows the required syntax for configuration files: Configuration variables may be declared as array parameters when describing multiple instances of the variable configuration. For example, a system may contain two network interfaces, each having a unique IP address and subnet mask (see ifconfig(1M)). An example of such a dec- laration is as follows: Note that there must be no requirements on the order of the files sourced. This means configuration files must not refer to variables defined in other configuration files, since there is no guarantee that the variable being referenced is currently defined. There is no protection against environment variable namespace collision in these configuration files. Programmers must take care to avoid such prob- lems. /etc/TIMEZONE The file contains the definition of the environment variable. This file is required by POSIX. It is sourced by at the same time the files are sourced. SEE ALSO
rc(1M). rc.config(4)