Hi azurite,
First, a suggestion: Don't be afraid to try things and watch what happens!

And, another suggestion: Instead of searching the web to try to figure out what a utility on your system will do, read the manual page for that utility on your system. For instance, the command:

Code:

man find

will show you the manual page for the find utility on your system.

You still haven't told us what shell you're using. The manual page for your shell will describe pipelines, the while loop construct, the read built-in utility, variable assignments, parameter expansions, and file redirections. And, the mv manual page will describe how it can be used to rename files.

Unlike Windows, UNIX systems determine the type of a file by its contents; not by its name.

The command: find . -name '*eddy_corrected_brain.nii.gz*' searches the file hierarchy rooted in the current directory (.) for files with names that contain the string eddy_corrected_brain.nii.gz proceeded and followed by strings of 0 or more characters (*) and writes the pathname of each matching filename on a line by itself. Note that I did NOT include an asterisk at the end of the pattern I used in the find commands I suggested because I thought you only wanted filenames ending in .gz; not filenames containing .gz followed by other arbitrary text.

Since pathnames cannot contain NUL bytes, this output will be a text file unless the pathnames produced are longer than the number of bytes your system allows in a line in a text file. The number of types allowed on all UNIX and Linux systems is at least 2048. The actual number on your system can be found using the command:

Code:

getconf LINE_MAX

With no file redirection (as above) the output is displayed on your terminal. If you redirect the output as in any of the following:

Code:

find . -name '*eddy_corrected_brain.nii.gz' > file
find . -name '*eddy_corrected_brain.nii.gz' > file.txt
find . -name '*eddy_corrected_brain.nii.gz' > file.pdf

the output file will be a text file. By convention, storing text in a file with the filename extension .pdf is a VERY bad idea, but the name you choose for your output does not in any way affect the output placed in that file by the find utility.

If you want to see what a shell script is doing, turn on tracing and watch what it does while it is running. For example to add tracing to the script:

Code:

set -xv
find . -name '*DTISiemensTCless*.bvec' -o -name '*DTISiemensTCless*.bval' |
while read -r path
do	dir="${path%/*}"
	file="${path##*/}"
	subjectnumber="${file%%DTI*}"
	ext="${file##*.}"
	echo mv "$path" "$dir/${subjectnumber}DTI.$ext"
done
set +xv

The set -xv at the start of the script turns tracing on and the set +xv at the end of the script turns tracing off.

In the above pipeline, find prints the pathnames of all filenames containing the string DTISiemensTCless that end with the string .bvec or (-o) with the string .bval, the read command sets the variable path to the contents of one of those lines of output from find and the while loop contains parameter expansions and variable assignments that set dir to the name of the directory specified in path, file to the last component of path , subjectnumber to the part of that file's name before the string DTI, ext to the file's extension (not including the period), and the mv command renames the file named by that line of output from find to be a file in the same directory, with the same subject number that was in the original file followed by the string DTI followed by the filename extension that was on the original file.