라즈베리파이 ro 읽기 모드 ro->rw

mkdir a 

 Read-only file system

/dev/mmcblk0p2 on / type ext4 (ro,relatime)

devtmpfs on /dev type devtmpfs (rw,relatime,size=1800568k,nr_inodes=84156,mode=755)

proc on /proc type proc (rw,nosuid,nodev,noexec,relatime)

sysfs on /sys type sysfs (rw,nosuid,nodev,noexec,relatime)

securityfs on /sys/kernel/security type securityfs (rw,nosuid,nodev,noexec,relatime)

tmpfs on /dev/shm type tmpfs (rw,nosuid,nodev)

devpts on /dev/pts type devpts (rw,nosuid,noexec,relatime,gid=5,mode=620,ptmxmode=000)

tmpfs on /run type tmpfs (rw,nosuid,nodev,size=786176k,nr_inodes=819200,mode=755)

tmpfs on /run/lock type tmpfs (rw,nosuid,nodev,noexec,relatime,size=5120k)

cgroup2 on /sys/fs/cgroup type cgroup2 (rw,nosuid,nodev,noexec,relatime,nsdelegate,memory_recursiveprot)

none on /sys/fs/bpf type bpf (rw,nosuid,nodev,noexec,relatime,mode=700)

systemd-1 on /proc/sys/fs/binfmt_misc type autofs (rw,relatime,fd=29,pgrp=1,timeout=0,minproto=5,maxproto=5,direct)

debugfs on /sys/kernel/debug type debugfs (rw,nosuid,nodev,noexec,relatime)

sunrpc on /run/rpc_pipefs type rpc_pipefs (rw,relatime)

mqueue on /dev/mqueue type mqueue (rw,nosuid,nodev,noexec,relatime)

tracefs on /sys/kernel/tracing type tracefs (rw,nosuid,nodev,noexec,relatime)

fusectl on /sys/fs/fuse/connections type fusectl (rw,nosuid,nodev,noexec,relatime)

configfs on /sys/kernel/config type configfs (rw,nosuid,nodev,noexec,relatime)

tmpfs on /run/user/1000 type tmpfs (rw,nosuid,nodev,relatime,size=393084k,nr_inodes=98271,mode=700,uid=1000,gid=1000)

/dev/sda on /mnt/a type ext4 (rw,relatime)

mount -o remount,rw /

# 상태가  ro 에서 rw 로 변경됨 

mount 

/dev/mmcblk0p2 on / type ext4 (rw,relatime)