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Test Your Knowledge in Computers #555
Difficulty: Easy
In C, if double b = 3.14159265359; printf("b=%10f ", b); then the output with be b=3.141593
True or False?
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pmgetconfig(3) [centos man page]

PMGETCONFIG(3)						     Library Functions Manual						    PMGETCONFIG(3)

NAME
pmGetConfig - return Performance Co-Pilot configuration variable C SYNOPSIS
#include <pcp/pmapi.h> char *pmGetConfig(const char *variable); #include <pcp/impl.h> char *__pmGetAPIConfig(const char *feature); cc ... -lpcp DESCRIPTION
The pmGetConfig function searches for variable first in the environment and then, if not found, in the Performance Co-Pilot (PCP) configu- ration file and returns the string result. If variable is not already in the environment, it is added with a call to putenv(3) before returning. The default location of the PCP configuration file is /etc/pcp.conf but this may be changed by setting PCP_CONF in the environment to a new location, as described in pcp.conf(5). The internal __pmGetAPIConfig function reports on features of the PCP library. It can be used to query support for multi-threading, secu- rity extensions, and other features. The pmconfig(1) utility provides command line access to both of these interfaces, and also provides a mechanism for listing all available variables and features that are valid arguments to these routines. RETURN VALUE
If variable is not found in either the environment nor the PCP configuration file then the return value is an empty string. If the PCP configuration file is not found then a fatal error message is printed and the process will exit(2) - although this sounds drastic, it is the only course of action available because the PCP configuration/installation is fatally flawed. If the pmGetConfig function returns a non-empty string, the returned value points into the environment and so changing it is a bad idea. This function returns the same type as the getenv(3) function (which should probably be a const char *). The __pmGetAPIConfig routine on the other hand returns NULL on failure to lookup the requested feature. It does not modify the environ- ment, and returns a pointer to a static read-only string which also should not be modified or freed by the caller. PCP ENVIRONMENT
Environment variables with the prefix PCP_ are used to parameterize the file and directory names used by PCP. On each installation, the file /etc/pcp.conf contains the local values for these variables. The $PCP_CONF variable may be used to specify an alternative configura- tion file, as described in pcp.conf(5). Values for these variables may be obtained programmatically using the pmGetConfig(3) function. SEE ALSO
PCPIntro(1), pmconfig(1), exit(2), PMAPI(3), getenv(3C), putenv(3C), pcp.conf(5), pcp.env(5) and environ(5). Performance Co-Pilot PCP PMGETCONFIG(3)

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PCP.CONF(5)							File Formats Manual						       PCP.CONF(5)

NAME
pcp.conf - the Performance Co-Pilot configuration and environment file SYNOPSIS
/etc/pcp.conf DESCRIPTION
When using Performance Co-Pilot (PCP) tools and utilities and when calling PCP library functions, a standard set of environment variables are defined in /etc/pcp.conf. These variables are generally used to specify the location of various PCP pieces in the file system and may be loaded into shell scripts by sourcing the /etc/pcp.env(5) shell script and queried by C/C++ programs using the pmGetConfig(3) library function. If a variable is already defined in the environment, the values in pcp.conf do not override those values, i.e. the values in pcp.conf serve as installation defaults only. Both the pcp.env and pcp.conf files are expected to be found in /etc by default. If required, the pcp.conf file may be relocated and PCP_CONF set in the environment to specify the full path to the new location. The pcp.env file can not be relocated (this is the only hard coded path required by PCP). The syntax rules for pcp.conf are as follows : 1. the general syntax is PCP_VARIABLE_NAME=variable value to end of line 2. lines that begin with # and all blank lines are ignored. 3. all variables must be prefixed with PCP_. This is a security issue - variables that do not have this prefix will be silently ignored. 4. there should be no space between the variable name and the literal = and no space between the = and the variable value (unless the value actually starts with a space). This is required because the pcp.conf file may be sourced directly by Makefiles as well as inter- preted by the pcp.env script and the pmGetConfig function. 5. variable values may contain spaces and should not be quoted. The pcp.env script automatically quotes all variable values from the character immediately following the = through to the end of the line. For further details and an explanation of the use of each variable, see the comments in the /etc/pcp.conf file itself. ENVIRONMENT
The PCP_CONF environment variable specifies an alternative path to the pcp.conf file. SEE ALSO
PCPIntro(1), PCPIntro(3), PMAPI(3), pmGetConfig(3) and pcp.env(5). Performance Co-Pilot PCP PCP.CONF(5)

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