Shell Programming and Scripting

echo "20091112_File_Name_40301" |sed -r 's/(.*[0-9])_(.*)_([0-9]*)/\2/'
File_Name

# a=20091112_abc_2343.txt
# b=`echo $a | tr -d '[0-9]_'`
# echo $b
abc.txt

for i in *.txt
do
     b=`echo "$i" | tr -d '[0-9]_'`
     mv "$i" "$b"
done

for i in *.txt
do
     b=${i#*_}
     mv "$i" "${b%_*}.txt"
done

for fsrc in *.txt; do
    fdst="${fsrc#*_}"
    fdst="${fdst%_*}.txt"
    mv "$fsrc" "$fdst"
done

8593425832_anything_blablabla_whateverstring_90543902.txt

anythingblablablawhateverstring.txt

anything_blablabla_whateverstring.txt

$ echo 20091112_File_Name_40301.txt |sed 's/[0-9]//g; s/^_*//;s/_*\./\./'
File_Name.txt

$ echo 20091112_abc_2343.txt |sed 's/[0-9]//g; s/^_*//;s/_*\./\./'
abc.txt

$ echo 20091112_xyz_2343.txt  |sed 's/[0-9]//g; s/^_*//;s/_*\./\./'
xyz.txt

$ ls -1
File_Name.txt
20100212_file_12_494849.txt
file_10.txt
19930101_xyz_292829.prn
 
$ ls | sed -E 's/^[1-9][0-9]{7}_(.*)_[0-9][0-9]*\.([^\.]*)/\1.\2/'
File_Name.txt
file_12.txt
file_10.txt
xyz.prn

for file in *
do
    new=$(echo "$file" | sed -E 's/^[1-9][0-9]{7}_(.*)_[0-9][0-9]*\.([^\.]*)/\1.\2/')
    [ "$file" = "$new" ] || mv "$file" "$new"
done