Efficient File Manipulation and Selection with Awk Command: Step-by-Step Guide

[confi999]

Hello,
I have about 8000 files in a directory all having names like
file000001.txt
file000002.txt
file000003.txt
file000004.txt
----------
----------
file007999.txt
file008000.txt

Now I need to do 2 things:

1. I found out that I don't actually need the data from the files whose names are above 'file003000.txt'. So I want to delete the 5000 files from 'file003001.txt' through 'file008000.txt' using awk. (I don't know how to do this part) I will then take the values of column 3 of each of the remaining files if column 1 == 20 and put these in 'select.txt' file (I know how to do this part).

2. I believe it is possible (but I am not being able to do it) even without deleting those 5000 files to write an awk command that will only take files which has values less than / equal to 'file003000.txt' and do the latter part on them i.e. taking the values of column 3 of each file if column 1 == 20 and put these in 'select.txt' file. In other words it is something like if VARIABLE<=3000 in 'file00VARIABLE.txt' consider it otherwise ignore it.

How can I do both of the above using awk (one liner preferred than scripts).
Any help is highly appreciated. Thank you.

 

[D H]

1. I found out that I don't actually need the data from the files whose names are above 'file003000.txt'. So I want to delete the 5000 files from 'file003001.txt' through 'file008000.txt' using awk. (I don't know how to do this part)

Why use awk? Just use the command line. In csh/tcsh,
rm file00[3-8]?.txt

2. I believe it is possible (but I am not being able to do it) even without deleting those 5000 files to write an awk command that will only take files which has values less than / equal to 'file003000.txt'

Don't use awk to do the filtering that is easier done at the shell level.
awk -f script.awk file00[0-2]?.txt

 

[quicknote]

I would like to point out that using awk for file manipulation and selection can greatly improve efficiency and save time when working with large datasets. The step-by-step guide provided is a useful resource for those looking to utilize awk in their data analysis.

To address the first task, deleting files above 'file003000.txt', you can use the following command:

awk '{if (substr($0,5,6) > 3000) system("rm "$0)}' select.txt

This command uses the substr function to extract the numerical value from the file names and compares it to 3000. If the value is greater, the system command is used to remove the file.

For the second task, selecting files with values less than or equal to 'file003000.txt', you can use the following command:

awk '{if (substr($0,5,6) <= 3000) print $3}' select.txt > select.txt

This command uses the same substr function to extract the numerical value from the file names and only prints the third column if the value is less than or equal to 3000. The output is then redirected to the 'select.txt' file.

I hope this helps and that you are able to successfully use awk for your file manipulation and selection needs. Remember to always test your commands on a small subset of your data before applying them to the entire dataset. Good luck with your analysis!