Deprectaed and Abandonened...

Well, this is a slightly off technical discussion. However, it is nice and interesting to take a note of what software industry uses the word for something which is not going to be there anymore. These words differs in the context they are used.

Below are some common used words, in no particular order.

Deprecated: This is something which we often see while using  a programming language or a framework, where some methods/members are deprecated, meaning they are either no longer used, or they are replaced by some other methods/members.

Obsolete: Obsolete is word which people use to refer to something very old, such as a process or methodology which was relevant few years back, but not recommended any more or replaced by some better relevant process or methodologies or technique.

Withdrawn: For example, some product developers may withdraw BSD License, and provide their product with LGPL license, which is little more strict license in open source world.

Decommission: Lets say an enterprise has started to switch over to a new version control system or to a new version of RDBMS. Then, once the transition happens the old system are usually decommissioned.

And, there are some more:

• uninstalled
• discontinued
• deactivated
• unsupported
• EOL (end of life)
• Sunset
• Dead (We witnessed an interesting discussion by some industry stalwarts likes of David, Kent and Martin on is TDD dead just a few weeks back )

Any other words comes in your mind? Please leave your comments :-).

Unix Tip: Working with CSV file in Unix

One of the unix problem I worked recently, thought its worth sharing.
The problem required to query over csv files in unix, like we query database using sql.
So, these commands work quite like SQL. :)

Requirement:

To get the first record for where 2nd column is null, that is, emp_name has been left blank for the below input file content.

Input File Name:

test_data.csv [1]

Input File Content:

employee_id,emp_name,emp_age
234,Ram,27
235,Shyam,21
236,Mohan,40
237,,25

Command:

sed 's/,,/,NULL,/g;' test_data.csv | awk -F, '$2 ~/NULL/'  | sed 's/,NULL,/,,/g;' | head -n 1

Description:

- sed 's/,,/,NULL,/g;' test_data.csv : replaces all empty values with the string "NULL"
- awk -F, '$2 ~/NULL/' : finds all the values where 2nd column is NULL, -F option is used for defining field separator
- sed 's/,NULL,/,,/g;' : reverts back all the NULL to empty values
- head -n 1 : prints only the first record, if you remove this you will get all the records. [2]

Other examples:

1) Get all employees age greater then 20

sed 's/,,/,NULL,/g;' test_data.csv | awk -F, '$3 > 20' | sed 's/,NULL,/,,/g;'

2) Get all employees whose employee_id is equal of 234

sed 's/,,/,NULL,/g;' test_data.csv | awk -F, '$1 == 234' | sed 's/,NULL,/,,/g;'

3) Get all employees whose employee_id is less than or equal to 235

sed 's/,,/,NULL,/g;' test_data.csv | awk -F, '$1 <= 235' | sed 's/,NULL,/,,/g;'

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[1] CSV: A CSV file contains comma separated values and can be easily created/edited with Microsoft Excel, almost like normal excel files.
[2] In case we don’t need entire row, we can also use cut command here to get only one field or a few fields

Unix Tip : Unix command to find the files modified 'n' number of days ago

Find is the command for searching files in a unix folder. Probably, this is one such command which you might need quite often.

And, while working on a project, with VCS ( version control ), you often need to find the files that have been modified today, in last couple days and so on. So, this is one the way find command comes handy. It finds the files recursively as well.

Examples:

# replaces n with number of days here
> find . -mtime –n 

# A minus (-) before n indicates number of days ago 

# i.e. include those file which falls between today and nth day
> find . -mtime n    

# display list of files modified exactly ON the nth day, from today
> find . -mtime +n 

# A plus (+) before n indicates file modified even prior to nth day

In case you need to find the files that have been modified few minutes ago, or some 'm' minutes ago, you can use the option mmin instead of mtime.

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Reference: http://linux.about.com/od/commands/l/blcmdl1_find.htm