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Top Forums UNIX for Dummies Questions & Answers Can we optimize this simple script ? Post 302276147 by otheus on Tuesday 13th of January 2009 06:40:11 AM
Old 01-13-2009
Quote:
Originally Posted by rajavu
It is recommended always to use the variable with quotes especially during comparison to avoid such errors . Am I right ?
Pretty much, though analytically, you can see that the variable will contain something. However, someone can change the code that breaks that condition.... so better to always quote.

You can also do this trick, often seen in older scripts:
Code:
if [ x$var = x ];then ....

while [ ${answer}x = Yx ]; then ....

Instead of quoting the variable, you pre- or postfix something to it AND the thing you compare it to.
 

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pthread_condattr_init(3T)												 pthread_condattr_init(3T)

NAME
pthread_condattr_init(), pthread_condattr_destroy() - initialize or destroy a condition variable attributes object. SYNOPSIS
PARAMETERS
attr Pointer to the condition variable attributes object to be initialized or destroyed. DESCRIPTION
initializes the condition variable attributes object attr with the default values for all attributes. The attributes object describes a condition variable in detail and is passed to the condition variable initialization function. When a condition variable attributes object is used to initialize a condition variable, the values of the individual attributes determine the characteristics of the new condition variable. Attributes objects act like additional parameters to object initialization. A single attributes object can be used in multiple calls to the function When a condition variable is initialized with an attributes object, the attributes are, in effect, copied into the condition variable. Consequently, any change to the attributes object will not affect any previously initialized condition variables. Once all condition vari- ables needing a specific attributes object have been initialized, the attributes object is no longer needed. The condition variable attributes and their default values are: The default value is If an initialized condition variable attributes object is reinitialized, undefined behavior results. destroys the condition variable attributes object attr. The destroyed condition variable attributes object ceases to exist and its resources are reclaimed. Using attr after it has been destroyed results in undefined behavior. A destroyed condition variable attributes object can be reinitialized using the function Condition variables that have been already initialized using this attributes object are not affected by the destruction of the condition variable attributes object. RETURN VALUE
Upon successful completion, and return zero. Otherwise, an error number is returned to indicate the error (the variable is not set). ERRORS
If any of the following occur, the function returns the corresponding error number: [ENOMEM] There is insufficient memory available in which to initialize the condition variable attributes object. [EINVAL] attr is not a valid condition variable attributes object. For each of the following conditions, if the condition is detected, the function returns the corresponding error number: [EINVAL] attr is not a valid condition variable attributes object. AUTHOR
and were derived from the IEEE POSIX P1003.1c standard. SEE ALSO
pthread_create(3T), pthread_condattr_getpshared(3T), pthread_cond_init(3T). STANDARDS CONFORMANCE
Pthread Library pthread_condattr_init(3T)
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