Changing mass file names?

Question

I have an issue about how to change orders of that sac files name. I mean I have this order but I need to change it to the second one and thes ecommands should be on the script. Additionally, this change must be done with using column numbers.

OLD

2007.084.00.22.50.8930_2007.084.01.26.10.1430.GE.ISP..BHZ.D.SAC
2007.084.00.22.51.2930_2007.084.01.26.54.8430.GE.ISP..BHN.D.SAC
2007.084.00.25.42.9430_2007.084.01.27.59.2430.GE.ISP..BHE.D.SAC

NEW

2007.084.01.26.10.1430_2007.084.00.22.50.8930.GE.ISP..BHZ.D.SAC
2007.084.01.26.54.8430_2007.084.00.22.51.2930.GE.ISP..BHN.D.SAC
2007.084.01.27.59.2430_2007.084.00.25.42.9430.GE.ISP..BHE.D.SAC

Let me write the code that I try to finish in this way (if the answers will be in that way, it will be more helpful for me) and I don't know how to continue to finish this process.

#!/bin/bash

for sacfile in *SAC
do

echo $sacfile
n2=`echo $sacfile | cut -c 24-45`
echo $n2

done 

Answer 1

Assuming they're fixed length filenames this should work.

#!/bin/bash

for sacfile in *SAC
do
    new_sacfile=${sacfile:23:22}_${sacfile:0:22}${sacfile:45}
    echo mv -v ${sacfile} ${new_sacfile}
done 

We're using bash's built in variable manipulation to cut up the file name and rearrange it to our desire. When you're happy you can remove the echo in front of the mv statement