树莓派系统（Linux）SD卡存储设备的命令行使用

本文介绍了SD卡读卡器通过usb连接到树莓派的挂载和卸载的操作，以及SD卡的格式化以及查看SD卡容量的命令行操作。mount umount mkfs.vfat df

 

当SD卡插入到树莓派板子上的时候/dev目录下会出现sda1的设备节点，有时候会出现sdb1或者sdc1设备节点。有的Linux系统上是mmcblk*的设备节点，可能和操作系统有关，也有可能是笔者连接SD卡的方式是通过一个USB hub的tf读卡器的原因。

sudo fdisk -l

 

值得注意的是：在系统一直运行中的时候，第一次插上SD卡，显示的是sda1，然后插拔SD卡后变成sdb1，再次插拔SD卡后变成sdc1，继续插拔SD卡，就一直是sdc1了。这可能和树莓派的系统有关，就是只能识别3个SD卡接入。reboot系统后，发现，不管SD卡热插拔多少次显示的设备节点都是sda1，在没有插SD卡时/dev目录只有sda设备节点。所以上面出现的sdb1和sdc1 可能是随机的。

SD卡的挂载：

sudo mkdir /mnt/sdcard

sudo mount -t vfat /dev/sda1 /mnt/sdcard/

因为是Windows分区，所以是vfat文件系统格式

mount -t vfat -o iocharset=utf8 /dev/sdb1 /mnt/usb/

指定中文编码格式为UTF-8

（经过上的挂载操作后发现：挂载成功后，将SD卡拔出，sudo fdisk -l下面没有sda1了，但是dev目录下仍然有sda1，查看/mnt/sdcard目录，文件仍然存在）

 

SD卡的卸载：

umount -v /mnt/sdcard/

 

SD卡的格式化操作：

1.从Linux中卸载SD卡

sudo umount -v /mnt/sdcard/

如果没有这一步操作：在格式化的时候就会出现如下错误：

pi@raspberrypi:/mnt/sdcard $ sudo mkfs.vfat /dev/sda1

mkfs.fat 4.1 (2017-01-24)

mkfs.vfat: /dev/sda1 contains a mounted filesystem.

pi@raspberrypi:/mnt/sdcard $

 

2.格式化SD卡

sudo mkfs.vfat /dev/sda1

3.重新挂载SD卡

sudo mount -t vfat /dev/sda1 /mnt/sdcard/

 

查看SD卡的总的容量和已使用过的容量以及剩余可以使用的容量

 df -h /dev/sda1

---

pi@raspberrypi:~ $ mount -h

Usage:
 mount [-lhV]
 mount -a [options]
 mount [options] [--source]  | [--target] 
 mount [options]  
 mount   []

Mount a filesystem.

Options:
 -a, --all               mount all filesystems mentioned in fstab
 -c, --no-canonicalize   don't canonicalize paths
 -f, --fake              dry run; skip the mount(2) syscall
 -F, --fork              fork off for each device (use with -a)
 -T, --fstab       alternative file to /etc/fstab
 -i, --internal-only     don't call the mount. helpers
 -l, --show-labels       show also filesystem labels
 -n, --no-mtab           don't write to /etc/mtab
     --options-mode 
                         what to do with options loaded from fstab
     --options-source 
                         mount options source
     --options-source-force
                         force use of options from fstab/mtab
 -o, --options     comma-separated list of mount options
 -O, --test-opts   limit the set of filesystems (use with -a)
 -r, --read-only         mount the filesystem read-only (same as -o ro)
 -t, --types       limit the set of filesystem types
     --source       explicitly specifies source (path, label, uuid)
     --target    explicitly specifies mountpoint
 -v, --verbose           say what is being done
 -w, --rw, --read-write  mount the filesystem read-write (default)
 -N, --namespace     perform mount in another namespace

 -h, --help              display this help
 -V, --version           display version

Source:
 -L, --label      synonym for LABEL=
 -U, --uuid        synonym for UUID=
 LABEL=           specifies device by filesystem label
 UUID=             specifies device by filesystem UUID
 PARTLABEL=       specifies device by partition label
 PARTUUID=         specifies device by partition UUID
                 specifies device by path
              mountpoint for bind mounts (see --bind/rbind)
                   regular file for loopdev setup

Operations:
 -B, --bind              mount a subtree somewhere else (same as -o bind)
 -M, --move              move a subtree to some other place
 -R, --rbind             mount a subtree and all submounts somewhere else
 --make-shared           mark a subtree as shared
 --make-slave            mark a subtree as slave
 --make-private          mark a subtree as private
 --make-unbindable       mark a subtree as unbindable
 --make-rshared          recursively mark a whole subtree as shared
 --make-rslave           recursively mark a whole subtree as slave
 --make-rprivate         recursively mark a whole subtree as private
 --make-runbindable      recursively mark a whole subtree as unbindable

For more details see mount(8).

pi@raspberrypi:~ $ umount -h

Usage:
 umount [-hV]
 umount -a [options]
 umount [options]  | 

Unmount filesystems.

Options:
 -a, --all               unmount all filesystems
 -A, --all-targets       unmount all mountpoints for the given device in the
                           current namespace
 -c, --no-canonicalize   don't canonicalize paths
 -d, --detach-loop       if mounted loop device, also free this loop device
     --fake              dry run; skip the umount(2) syscall
 -f, --force             force unmount (in case of an unreachable NFS system)
 -i, --internal-only     don't call the umount. helpers
 -n, --no-mtab           don't write to /etc/mtab
 -l, --lazy              detach the filesystem now, clean up things later
 -O, --test-opts   limit the set of filesystems (use with -a)
 -R, --recursive         recursively unmount a target with all its children
 -r, --read-only         in case unmounting fails, try to remount read-only
 -t, --types       limit the set of filesystem types
 -v, --verbose           say what is being done
 -q, --quiet             suppress 'not mounted' error messages
 -N, --namespace     perform umount in another namespace

 -h, --help              display this help
 -V, --version           display version

For more details see umount(8).