ProgrammingExamples - User contributions [en]

Python

2012-09-22T21:51:54Z

Bandtank:

= Python =
[http://python.org/ The Python programming language]
* Is [http://python.org/download/ Freely available]
* Runs [http://python.org/about/#python-runs-everywhere "everywhere"]
* Is interpreted (byte code compiled)
* Has efficient high level [http://docs.python.org/tutorial/datastructures.html data structures]
* Provides simple, effective [http://en.wikipedia.org/wiki/Object-oriented_programming object oriented programming]
* Has dynamic typing ([http://en.wikipedia.org/wiki/Duck_typing duck typing])
* Has an extensive [http://docs.python.org/library/index.html standard library] as well as many [http://pypi.python.org/pypi 3rd party additions]
* Is readily extensible using code written in C or C++
There is [http://docs.python.org/ extensive online documentation], including a [http://docs.python.org/tutorial/index.html tutorial].
----
=== Python Programming Examples ===
* [[Python/Smtplib|Send Emails with SMTP Library]]
* [[Python/ManyArgs|Handle many parameters under maintenance]]
* [[Python/UserPasswords|Getting a user name and (hidden text) password]]
* [[Python/DictAsSwitch|How to do a switch/case statement in Python]]
* [[Python/ThreePartOperator|How to mimic C's a = b ? b : c]]
* [[Python/Query MySQL databases using a custom class]]

Bash

2012-02-16T22:04:11Z

Bandtank:

* [[Bash/LoopOverFiles|Loop over files]]
* [[Bash/Parsing command line arguments using getopts|Parsing command line arguments using getopts]]
* [[Bash/Regular expression example using grep and sed|Regular expression example using grep and sed]]

Bash

2011-10-05T16:42:56Z

Bandtank:

* [[Bash/LoopOverFiles|Loop over files]]
* [[Bash/Parsing command line arguments using getopts|Parsing command line arguments using getopts]]

Bash/Parsing command line arguments using getopts

2011-10-05T16:41:25Z

Bandtank: moved Bash/commandLineArgs to Bash/Parsing command line arguments using getopts

Handling command line arguments can be done many ways, but few will be as elegant and streamlined as the built-in shell command called getopts. Note: getopt is the older version and should not be used as it is far less robust.

Getopts shifts the data and sets an exit status of false when there is nothing left to do. Because of this behavior, getopts works well in a while loop as follows:

<syntaxhighlight lang="bash">
while getopts ...; do
...
done
</syntaxhighlight>

Often used in conjunction with getopts is the following conditional statement to force a certain number of arguments to be supplied:

<syntaxhighlight lang="bash">
#Check to see if the right number of arguments were supplied
if [ $# -lt 1 ] ; then
...
fi
</syntaxhighlight>

The following script shows the usage of getopts. Getopts can't handle long options and will stop processing arguments when it hits the "--" argument (end of options). To specify an argument, the first letter of the word to be used as a switch is placed after the getopts command with an optional ":" if it also requires an additional parameter. An example program can be seen below.

<syntaxhighlight lang="bash">
#!/bin/bash

#Set a default value for the $cell variable
cell="test"

#Check to see if at least one argument was specified
if [ $# -lt 1 ] ; then
echo "You must specify at least 1 argument."
exit 1
fi

#Process the arguments
while getopts c:hin: opt
do
case "$opt" in
c) cell=$OPTARG;;
h) usage;;
i) info="yes"
n) name=$OPTARG;;
\?) usage;;
esac
done
</syntaxhighlight>

Example usages:

<syntaxhighlight lang="bash">
getopts_example.sh -c test1 -n test2
getopts_example.sh -c test3 -i
getopts_example.sh -h
getopts_example.sh -a
</syntaxhighlight>

Example 1 would assign "test1" to the $cell variable and "test2" to the $name variable.

Example 2 would assign "test3" to the $cell variable, $name would not exist, and "yes" would be assigned to $info.

Example 3 would call the usage function.

Example 4 would cause getopts to display an error to stderr and then exit after calling the usage function.

Bash/commandLineArgs

2011-10-05T16:41:25Z

Bandtank: moved Bash/commandLineArgs to Bash/Parsing command line arguments using getopts

#REDIRECT [[Bash/Parsing command line arguments using getopts]]

Bash/Parsing command line arguments using getopts

2011-10-05T02:02:31Z

Bandtank:

Bash/Parsing command line arguments using getopts

2011-10-05T01:56:26Z

Bandtank:

Handling command line arguments can be done many ways, but few will be as elegant and streamlined as the built-in shell command called getopts. Note: getopt is the older version and should not be used as it is far less robust.

Getopts shifts the data and sets an exit status of false when there is nothing left to do. Because of this behavior, getopts works well in a while loop as follows:

<syntaxhighlight lang="bash">
while getopts ...; do
...
done
</syntaxhighlight>

Often used in conjunction with getopts is the following conditional statement to force a certain number of arguments to be supplied:

<syntaxhighlight lang="bash">
#Check to see if the right number of arguments were supplied
if [ $# -lt 1 ] ; then
...
fi
</syntaxhighlight>

The following script shows the usage of getopts. Getopts can't handle long options and will stop processing arguments when it hits the "--" argument (end of options). To specify an argument, the first letter of the word to be used as a switch is placed after the getopts command with an optional ":" if it also requires an additional parameter. An example program can be seen below.

<syntaxhighlight lang="bash">
#!/bin/bash

#Set a default value for the $cell variable
cell="test"

#Check to see if at least one argument was specified
if [ $# -lt 1 ] ; then
echo "You must specify at least 1 argument."
exit 1
fi

#Process the arguments
while getopts c:hi: opt
do
case "$opt" in
c) cell=$OPTARG;;
h) usage;;
n) name=$OPTARG;;
\?) usage;;
esac
done
</syntaxhighlight>

Example usages:

<syntaxhighlight lang="bash">
getopts_example.sh -c test1 -n test2
getopts_example.sh -c test3
getopts_example.sh -h
getopts_example.sh -a
</syntaxhighlight>

Example 1 would assign "test1" to the $cell variable and "test2" to the $name variable.

Example 2 would assign "test3" to the $cell variable and $name would not exist.

Example 3 would call the usage function.

Example 4 would cause getopts to display an error to stderr and then exit after calling the usage function.