adding number and string to each line in a data file

teresevo1 · 04-10-2010, 02:21 PM

I have a very large data file, with 3 numbers in each line, ex. 3 4 5 ; 6 7 8 ....

I want to add two numbers (0 and 1) at the end of every line, and a string at the beginning of the line. Does anyone know a efficient way to do so?

jschiwal · 04-10-2010, 02:36 PM

Please provide more information on what these numbers are for, and what determines the forth number and the string. That may determine the best tool to use. For regular formatted records that may require computation on these numbers, awk my be the best tool to use, but more details are needed to know for sure. You may need a general purpose language such as perl or python if you need access to one of their libraries to carry out the task.

teresevo1 · 04-10-2010, 02:48 PM

the number at the end of the lines are the same for every line in the file, representing the name of the dataset.

Sergei Steshenko · 04-10-2010, 02:58 PM

Quote:

Originally Posted by teresevo1

I have a very large data file, with 3 numbers in each line, ex. 3 4 5 ; 6 7 8 ....

I want to add two numbers (0 and 1) at the end of every line, and a string at the beginning of the line. Does anyone know a efficient way to do so?

An efficient way would be to write a script. Or even a "C" program - the task is very simple.

Do you know Perl or "C" ?

pixellany · 04-10-2010, 03:03 PM

To add something to the beginning or end of each line in a file, I would use SED.

Examples:

Code:

Adding hello to the beginning of every line:
sed 's/^/hello /' filename > newfilename

Adding "23" to the end of every line:
sed 's/$/ 23/' filename > newfilename

Very good SED tutorial here:
http://www.grymoire.com/Unix/Sed.html

jschiwal · 04-10-2010, 04:45 PM

Since you mentioned doing both:

Code:

sed 's/^.*$/hello & 23/'  filename > newfilename

grail · 04-10-2010, 10:12 PM

Or just a simple awk:

Code:

 awk '{print "string "$0" 0 1"}' file

ghostdog74 · 04-11-2010, 12:03 AM

@OP, if you need to add things to the front and back of strings, just print them out...like what grail posted. Or this

Code:

awk '{$0="string "$0" 0 1"}1' file