Deleting specific files based on filename from terminal

Question

I have a directory containing files with names

rho_0.txt
rho_5000.txt
rho_10000.txt
rho_150000.txt
rho_200000.txt

and so on. I would like to delete all those that are a multiple of 5000.

I tried the following: printf 'rho_%d.txt\n' $(seq 5000 10000 25000) | rm, but that gave me the response rm: missing operand.

Is there another way to do this?

Answer 1

You don't need a loop or extra commands where you have Bash Shell Brace Expansion.

rm -f rho_{0..200000..5000}.txt

Explanation: {start..end..step}. The -f to ignore prompt on non-existent files.

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P.s. To keep safety and check which files will be deleted, please do a test first with:

ls -1 rho_{0..200000..5000}.txt

Answer 2

rm doesn't read from standard input. You could do:

for i in $(seq 5000 5000 25000); do
    rm -i rho_${i}.txt
done

I include the -i option to rm to prompt before removal so that you can verify the behavior. Once you're confident it's doing what you want, you could omit that option.

Edit: Alternatively, you could do:

for ((i = 5000; i <= 25000; i += 5000)); do
    rm -i rho_${i}.txt
done

That form may be more familiar if you've done any programming.

Answer 3

You cannot pipe to a program as if the content of the pipe were arguments. It's sent through stdin.

You should use xarg for this purpose :

printf 'rho_%d.txt\n' $(seq 5000 10000 25000) | xargs rm 

but first you can give a try with echo to see if everything is as you intend :

printf 'rho_%d.txt\n' $(seq 5000 10000 25000) | xargs echo

Answer 4

Someone correct me if I'm wrong, but if all the files that start with rho_ are of this form, isn't it equivalent to do

rm rho_0.txt rho_*[05]000.txt

Since a number (other than 0) is a multiple of 5000 if and only if it ends in 0000 or 5000.

(0 is a special case, since it is a multiple of 5000, but is typically written without additional leading zeros. If you didn't intend to include 0, then take it out of the above line.)

Of course this should only be used if all the rho_*.txt files in your directory have the desired form. Don't use it if your directory also contains rho_please_dont_delete_me_5000.txt.

(Math note: This works precisely because all the prime factors of 5000, namely 2 and 5, are also prime factors of the base we are working in, 10. Equivalently, there is a sufficiently large power of 10 (namely 10000) which is divisible by 5000. There is no similar trick for matching all those which are multiples of 3000.)