environment variable

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environment variable

(programming, operating system)
A variable that is bound in the current environment. When evaluating an expression in some environment, the evaluation of a variable consists of looking up its name in the environment and substituting its value.

Most programming languages have some concept of an environment but in Unix shell scripts it has a specific meaning slightly different from other contexts. In shell scripts, environment variables are one kind of shell variable. They differ from local variables and command line arguments in that they are inheritted by a child process. Examples are the PATH variable that tells the shell the file system paths to search to find command executables and the TZ variable which contains the local time zone. The variable called "SHELL" specifies the type of shell being used.

These variables are used by commands or shell scripts to discover things about the environment they are operating in. Environment variables can be changed or created by the user or a program.

To see a list of environment variables type "setenv" at the csh or tcsh prompt or "set" at the sh, bash, jsh or ksh prompt.

In other programming languages, e.g. functional programming languages, the environment is extended with new bindings when a function's parameters are bound to its actual arguments or when new variables are declared. In a block-structured procedural language, the environment usually consists of a linked list of activation records.
This article is provided by FOLDOC - Free Online Dictionary of Computing (foldoc.org)

environment variable

An item of memory-resident data that provides a mechanism for users, applications and the operating system to interact with each other. Set up in memory by the operating system each time it is booted, the variables hold the current environment configuration, such as computer and login name, CPU type and the names of the system, application, home and temporary folders.

Command Line Assistance
A common environment variable is the Path, which holds any number of folder hierarchies that the OS can search when a program is run at the command line so that the full path to the executable does not have to be explicitly entered each time. See path environment variable and path.
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References in periodicals archive ?
None of the significant neighborhood environment variables in the three models had significantly different between-person (cross-sectional) and within-person (longitudinal) effect estimates (results not shown), suggesting that there was little confounding by uncontrolled time-constant factors, including time-constant self-selection factors.
The environment variable, without considering whether it is uncertain or complex, influences the organizational innovation, which means that the service companies take into consideration the behavior of external factors that affect the organization to conduct activities of organizational innovation; this is related to the works of: Damanpour (2010), who states that innovations are influenced by the market conditions (2); and McCrea and Betts (2008), who indicate that innovations allow companies to better respond to changes in the environment.
As such, the institutional environment variable of regulatory quality should mediate the expected relationship between future orientation and corporate governance practices.
The 175 firms from the study were placed into "Little-To-Moderate," "Average" and "High" groups based on their mean response to the composite measure of the Collaborative NPD Environment variable. The sample's mean response to the composite measure of the Collaborative NPD Environment variable was 3.95 ([sigma]=0.66) as noted in Table II.
added to the predictive equation (Step 1), the R-squared change for the comfort in the university environment variable set (Step 2) was .04, [DELTA]F(3, 146) = 2.89, p [less than or equal to] .05.
Extant theoretical perspectives on career largely continue to incorporate constructs that reflect predominantly person rather than environment variables. Some of these variables deal with fit, or the nexus between person and environment, and include congruence (Holland, 1997), correspondence (Dawis, 1996), and self-concept implementation (Super, Savickas, & Super, 1996).
The name of the web site making the request can be passed to the program in the QUERY_STRING environment variable. Six steps are required to obtain the users location as follows:
Independent Variables: The independent variables are classified into two groups- ecological and institutional environment variables. The three ecological variables are: (1) prior foundings F(t-1), the total number of firms founded in the year prior to the event; (2) prior deaths D(t-1), the total number of firms that withdrew in the previous year; and (3) population density N(t), the total number of firms alive at the beginning of each year.
An environmental variable would be a pure moderator if there is a significant interaction between it and market orientation as a determinant of performance, but no significant relationship between the environment variable and performance or market orientation.
[chi square] Tests were used to compare percentages of PSH across levels of environment variable. Qualitative data underwent thematic analysis.

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