ENV - Examples

Examples

To clear the environment (creating a new environment without any existing environment variables) for a new shell:

env -i /bin/sh

To launch the X Window application xcalc and have it appear on a different display:

env DISPLAY=foo.bar:1.0 xcalc

Here is the code of a very simple Python script:

#!/usr/bin/env python2 print "Hello World."

In this example, /usr/bin/env is the full path of the env command. The environment is not altered.

Note that it is possible to specify the interpreter without using env, by giving the full path of the python interpreter. A problem with that approach is that on different computer systems, the exact path may be different. By instead using env as in the example, the interpreter is searched for and located at the time the script is run. This makes the script more portable, but also increases the risk that the wrong interpreter is selected because it searches for a match in every directory on the executable search path. It also suffers from the same problem in that the path to the env binary may also be different on a per-machine basis.

Read more about this topic:  ENV

Famous quotes containing the word examples:

    “It is hardly to be believed how spiritual reflections when mixed with a little physics can hold people’s attention and give them a livelier idea of God than do the often ill-applied examples of his wrath.”
    —G.C. (Georg Christoph)

    “Histories are more full of examples of the fidelity of dogs than of friends.”
    —Alexander Pope (1688–1744)

    “In the examples that I here bring in of what I have [read], heard, done or said, I have refrained from daring to alter even the smallest and most indifferent circumstances. My conscience falsifies not an iota; for my knowledge I cannot answer.”
    —Michel de Montaigne (1533–1592)