Linux下BUG系列：ubuntu16.04下U盘变只读Read-Only
有时在ubuntu16.04下使用U盘发现无法写入，多次拔插无效，但是Upan明明在Win下用得好好的啊。。
修复
执行命令
tail -f /var/log/syslog
在系统日志中可以看到你的U盘插入的消息
Jul 16 15:18:22 lowfree02 gnome-session[1701]: (nautilus:3868): Gtk-CRITICAL **: gtk_icon_theme_get_for_screen: assertion 'GDK_IS_SCREEN (screen)' failed
Jul 16 15:18:22 lowfree02 gnome-session[1701]: (nautilus:3868): GLib-GObject-WARNING **: invalid (NULL) pointer instance
Jul 16 15:18:22 lowfree02 gnome-session[1701]: (nautilus:3868): GLib-GObject-CRITICAL **: g_signal_connect_object: assertion 'G_TYPE_CHECK_INSTANCE (instance)' failed
Jul 16 15:18:22 lowfree02 dbus[697]: [system] Activating via systemd: service name='org.freedesktop.hostname1' unit='dbus-org.freedesktop.hostname1.service'
Jul 16 15:18:22 lowfree02 systemd[1]: Starting Hostname Service...
Jul 16 15:18:22 lowfree02 dbus[697]: [system] Successfully activated service 'org.freedesktop.hostname1'
Jul 16 15:18:22 lowfree02 systemd[1]: Started Hostname Service.
Jul 16 15:18:23 lowfree02 org.gnome.Nautilus[1547]: (nautilus:3676): GLib-GIO-CRITICAL **: g_file_get_parse_name: assertion 'G_IS_FILE (file)' failed
Jul 16 15:18:23 lowfree02 kernel: [23859.535467] FAT-fs (sdb4): error, corrupted directory (invalid entries)
Jul 16 15:18:23 lowfree02 kernel: [23859.535471] FAT-fs (sdb4): Filesystem has been set read-only
从最后一行看到：
Jul 16 15:18:23 lowfree02 kernel: [23859.535471] FAT-fs (sdb4): Filesystem has been set read-only
记下U盘盘符sdb4
另外要知道自己U盘的挂载名，一般在/media下可看到，然后将其umount
# ls /media
lowfree
# umount /media/lowfree/Ubuntu\ 16.0/
然后再修复一下
# sudo dosfsck -v -a /dev/sdb4
最后再重新挂载或重新拔插一下即可～
