2022-04-12 11:14PM [/home/zzh/aaa]$>lh total 8.0K -rw-rw-r-- 1 zzh users 0 Apr 12 05:08 c.txt -rw-rw-r-- 1 zzh users 0 Apr 12 05:08 b.txt -rw-rw-r-- 1 zzh users 0 Apr 12 05:08 a.txt 2022-04-12 11:14PM [/home/zzh/aaa]$>for x in *.txt; do >> mv $x $x.bak >> done 2022-04-12 11:16PM [/home/zzh/aaa]$>lh total 8.0K -rw-rw-r-- 1 zzh users 0 Apr 12 05:08 c.txt.bak -rw-rw-r-- 1 zzh users 0 Apr 12 05:08 b.txt.bak -rw-rw-r-- 1 zzh users 0 Apr 12 05:08 a.txt.bak