Python: class to read configuration file (both INI-like or regular)

This class can read both types of config file: ini-style and regular (with no section header)

Python: A very good Popen usage to execute command

This function allow you to execute a command or piped commands using subprocess Popen. It allows you to use shell or non-shell (for better security) to execute.

Java: Print text to stdout, get input from stdin

Python: argparse – quick on parameters

Below is an example for using argparse:


Unix: Schedule a crontab

cron(8) examines cron entries once every minute.

The time and date fields are:

field          allowed values
-----          --------------
minute         0-59
hour           0-23
day of month   1-31
month          1-12 (or names, see below)
day of week    0-7 (0 or 7 is Sun, or use names)

A field may be an asterisk (*), which always stands for "first-last".

Ranges  of  numbers are allowed.  Ranges are two numbers separated with a hyphen.  The specified range is inclusive.  For example, 8-11 for an "hours" entry specifies execution at
hours 8, 9, 10 and 11.

Lists are allowed.  A list is a set of numbers (or ranges) separated by commas.  Examples: "1,2,5,9", "0-4,8-12".

Step values can be used in conjunction with ranges.  Following a range with "<number>" specifies skips of the number’s value through the range.  For example, "0-23/2" can be  used
in  the  hours  field  to  specify  command execution every other hour (the alternative in the V7 standard is "0,2,4,6,8,10,12,14,16,18,20,22").  Steps are also permitted after an
asterisk, so if you want to say "every two hours", just use "*/2".

Names can also be used for the "month" and "day of week" fields.  Use the first three letters of the particular day or month (case doesn’t matter).  Ranges or lists of  names  are
not allowed.

The  "sixth"  field (the rest of the line) specifies the command to be run.  The entire command portion of the line, up to a newline or % character, will be executed by /bin/sh or
by the shell specified in the SHELL variable of the cronfile.  Percent-signs (%) in the command, unless escaped with backslash (\), will be changed into  newline  characters,  and
all data after the first % will be sent to the command as standard input.

Note:  The day of a command’s execution can be specified by two fields — day of month, and day of week.  If both fields are restricted (ie, aren’t *), the command will be run when
either field matches the current time.  For example,
"30 4 1,15 * 5" would cause a command to be run at 4:30 am on the 1st and 15th of each month, plus every Friday.

# use /bin/sh to run commands, no matter what /etc/passwd says
# mail any output to ‘paul’, no matter whose crontab this is
# run five minutes after midnight, every day
5 0 * * *       $HOME/bin/daily.job >> $HOME/tmp/out 2>&1
# run at 2:15pm on the first of every month -- output mailed to paul
15 14 1 * *     $HOME/bin/monthly
# run at 10 pm on weekdays, annoy Joe
0 22 * * 1-5    mail -s "It’s 10pm" joe%Joe,%%Where are your kids?%
23 0-23/2 * * * echo "run 23 minutes after midn, 2am, 4am ..., everyday"
5 4 * * sun     echo "run at 5 after 4 every sunday"