Ls
The ls[1] command lists directory contents e.g.
ralph@c3po:/$ ls -l total 2475995 drwxr-xr-x 2 root root 12288 Jun 28 08:25 bin drwxr-xr-x 5 root root 3072 Jun 29 07:53 boot drwxr-xr-x 21 root root 3960 Aug 19 08:13 dev drwxr-xr-x 175 root root 12288 Aug 19 08:13 etc -rw-r--r-- 1 root root 2535280640 Dec 4 2021 hdd drwxr-xr-x 8 root root 4096 Feb 26 21:10 home -rw-r--r-- 1 root root 0 May 7 00:50 image lrwxrwxrwx 1 root root 31 Jun 28 08:26 initrd.img -> boot/initrd.img-5.10.0-15-amd64 lrwxrwxrwx 1 root root 31 Jun 28 08:26 initrd.img.old -> boot/initrd.img-5.10.0-13-amd64 drwxr-xr-x 18 root root 4096 Mar 30 07:41 lib drwxr-xr-x 2 root root 4096 Mar 30 07:41 lib32 drwxr-xr-x 2 root root 4096 Mar 30 07:41 lib64 drwx------ 2 root root 16384 Aug 6 2020 lost+found drwxr-xr-x 6 root root 4096 Jul 5 2021 media drwxr-xr-x 27 root root 4096 Jul 29 17:32 mnt drwxr-xr-x 8 root root 4096 Aug 7 2020 newvar drwxr-xr-x 2 root root 4096 Aug 7 2020 oldhome drwxr-xr-x 2 root root 4096 Aug 7 2020 oldvar drwxr-xr-x 5 root root 4096 Jan 26 2016 opt dr-xr-xr-x 401 root root 0 Aug 19 08:12 proc drwx------ 23 root root 4096 Aug 19 08:16 root drwxr-xr-x 39 root root 1200 Aug 19 19:26 run drwxr-xr-x 2 root root 12288 Jun 28 08:25 sbin drwxr-xr-x 6 root root 4096 Dec 14 2021 snap drwxr-xr-x 2 root root 4096 Jan 24 2019 srv dr-xr-xr-x 13 root root 0 Aug 19 08:12 sys drwxrwxrwt 15 root root 12288 Aug 19 19:18 tmp drwxr-xr-x 13 root root 4096 Dec 14 2021 usr drwxr-xr-x 14 root root 4096 Dec 14 2021 var drwxr-xr-x 8 root root 4096 Aug 19 08:18 virtual lrwxrwxrwx 1 root root 28 Jun 28 08:26 vmlinuz -> boot/vmlinuz-5.10.0-15-amd64 lrwxrwxrwx 1 root root 28 Jun 28 08:26 vmlinuz.old -> boot/vmlinuz-5.10.0-13-amd64