进入想要查看的目录

root@ubuntu20:/# ls
bin  boot  cdrom  dev  etc  home  lib  lib32  lib64  libx32  lost+found  media  mmkv.default  mmkv.default.crc  mnt  opt  path  proc  root  run  sbin  snap  srv  swapfile  sys  tmp  usr  var

执行命令

ls -d */ | tr -d '/' > dir.txt

查看结果

root@ubuntu20:/# cat dir.txt 
bin
boot
cdrom
dev
etc
home
lib
lib32
lib64
libx32
lost+found
media
mnt
opt
path
proc
root
run
sbin
snap
srv
sys
tmp
usr
var