Change the numerical sequence in filenames using bash/shell command-CodePudding

I have a group of files named in numerical sequence order from 1 to 1000,

s_nn_1.txt, s_nn_2.txt ..... s_nn_1000.txt .

I want to change the name of the file in a different sequence order as,

s_nn_1001.txt, s_nn_1002.txt .... s_nn_2000.txt .

I tried using two variables in 'for' loop but didn't work.

 for i in {1..1000}
do
for j in {1001..2000}
do
mv s_nn_"$i".txt s_nn_"$j".txt
done
done

Can you give any suggestions?

CodePudding user response：

In plain bash:

for ((i = 1; i <= 1000;   i)); do
    mv -i s_nn_$i.txt s_nn_$((i   1000)).txt
done

CodePudding user response：

While not an issue for OP's example, overlapping filenames should be considered when deciding on the order to perform the mv's.

If OP were going from {1..1000} to {500..1500}, half the files will be lost (eg, mv file1 file500 will overwrite the current file500, and later mv file500 file1000 will actually be making a copy of the original file1 and saving as file1000).

Generally speaking:

if increasing the numeric values then process the files in reverse numeric order
if decreasing the numeric values then process the files in (normal) numeric order

Applying this to OP's current code, and knowing the increase is 1000:

for i in {1000..1}
do
    mv s_nn_"$i".txt s_nn_"$((i 1000))".txt
done