Removing Middle Characters From File Name in Bash

Question

I'm new to text handling in bash and have hundreds of files with varying names:

TS_01_001_21.0.tif
TS_10_005_-21.0.tif
TS_21_010_-45.0.tif

I want to remove the middle section and the extension so the files look like:

TS_01_21.0
TS_10_-21.0
TS_21_-45.0

So far I have:

for f in *.tif;do 
   mv "${f}" "${f%.tif}"
done

To remove the extension, but I can't figure out how to remove the middle three characters. Any help would be greatly appreciated, thank you!

Answer 1

Assumptions:

• middle always means 3 digits plus an underscore (_)
• there is only the one (aka middle) occurrence of 3 digits plus an underscore (_)
• the extension is always .tif

One idea using a pair of parameter substitutions to remove the unwanted characters:

for f in TS_01_001_21.0.tif TS_10_005_-21.0.tif TS_21_010_-45.0.tif
do
    newf="${f//[0-9][0-9][0-9]_/}"
    newf="${newf/.tif/}"
    if [[ -f "${newf}" ]] 
    then
        # addressing comment/question re: what happens if two source files are modified to generate the same new file name
        echo "WARNING: ${newf} already exists. [ source: ${f} ]"
    else
        echo mv "${f}" "${newf}"
    fi
done

This generates:

mv TS_01_001_21.0.tif TS_01_21.0
mv TS_10_005_-21.0.tif TS_10_-21.0
mv TS_21_010_-45.0.tif TS_21_-45.0

Once satisfied with the result OP can remove the echo in order to perform the actual file renames.