Linux Ask! is a Q & A web site specific for Linux related questions. Questions are collected, answered and audited by experienced Linux users.
Simple date calculation using date command
Answer:
Date command is useful to calculate date, e.g. Assume today is 2011-01-15
1. Find a date in the past, e.g. 60 days ago
# date --date='60 days ago' "+%Y-%m-%d"
2010-11-162. Find a date in the future, e.g. 60 days in the future
# date --date='60 days' "+%Y-%m-%d"
2011-03-16Find the process ID of a running program
Answer:
The easiest way to get all the process IDs of a running program in Linux, see the following example:
# pidof apache2
29747 29745 29700 29698 29696 29695 29687 29678 29677 29664 23931How to ignore blank lines when creating the diff of two files
Answer:
By default, the diff command will also compare the blank line of two files.
To ignore them, use:
# diff -B a.txt b.txt
Create a short URL from command
Answer:
TinyUrl has a simple api for creating short URL for any web site.
E.g. Assume http://example.com
# curl 'http://tinyurl.com/api-create.php?url=http://example.com/'
http://tinyurl.com/kotu
Display timestamp information in command history
Answer:
When using the history command, it only shows the command number and the command itself. But sometimes it is useful to know when this command was executed, i.e. the timestamp. To do so, following the instructions below:
# export HISTTIMEFORMAT='%F %T '
Then type history again
# history
..
260 2010-12-23 19:22:07 ls
261 2010-12-23 19:22:07 pwd
...
That's all.
