mjhjmtu

I want to move all files that contain a number greater than 25 (at least on one instance) but don't contain any number smaller than 25 after the string >randomnumber_xxx_ to a specific folder.

Example of a file that needs to be moved:

>23424_xxx_26
>331134_xxx_27
>6634_xxx_30

Example of a file that doesn't need to be moved:

>22234_xxx_20
>434534_xxx_27

So, the first issue is to detect the files that needs to be moved.

This could be done using grep:

grep -q -E '^>.*_(1?[0-9]|2[0-4])$'
grep -q -E '^>.*_(2[5-9]|[3-9][0-9]|[0-9]3,)$'

These commands would return true if the input data contained a line that matched the given extended regular expressions.

The expression _(1?[0-9]|2[0-4])$ would match any positive integer less than 25 occurring at the end of a line after an underscore, and _(2[5-9]|[3-9][0-9]|[0-9]3,)$ matches any positive integer greater than or equal to 25 at the end of the line after an underscore (assuming there are no zero-filled integers such as 002). We also match the > at the start of the line. The -q option would stop grep from actually outputting anything (we're only interested in whether we could find one of these lines or not).

For a file to be copied, the first grep must return false and the second grep must return true.

Applying this to each file of a directory (in this case regardless of what the files are called as you did not say anything about this):

for filename in ./*; do
 [ ! -f "$filename" ] && continue

 if ! grep -q -E '^>.*_(1?[0-9]|2[0-4])$' "$filename" &&
 grep -q -E '^>.*_(2[5-9]|[3-9][0-9]|[0-9]3,)$' "$filename"
 then
 mv -i "$filename" /some/destination
 fi
done

This would move the files that fulfil the requirements to some destination directory at /some/destination. The -i option to mv would cause the utility to ask for confirmation before overwriting an already existing file with the same name as the file being moved.

The first [ ! -f ... ] test in the loop would skip anything in the directory that is not a regular file (or a symbolic link to a regular file).