depuser@TSDEP61:/csdn$ ls
1.txt 2.txt 3.txt 4.txt 5.txt
depuser@TSDEP61:/csdn$ for i in `ls`; do mv -f $i `echo "text_"$i`; done
depuser@TSDEP61:/csdn$ ls
text_1.txt text_2.txt text_3.txt text_4.txt text_5.txt
depuser@TSDEP61:/csdn$ rename 's/\.txt/\.csv/' *
depuser@TSDEP61:/csdn$ ls
text_1.csv text_2.csv text_3.csv text_4.csv text_5.csv