linux - shell 安装并检查方向是否存在

Question

只是在我的安装 shell 脚本中寻找一些帮助，想知道是否有人可以建议我如何让它检查安装点处的目录是否存在并且是否为空，或者如果它不存在则由脚本创建

#!/bin/bash

MOUNTPOINT="/myfilesystem"

if grep -qs "$MOUNTPOINT" /proc/mounts; then
    echo "It's mounted."
else
    echo "It's not mounted."

    mount "$MOUNTPOINT"

    if [ $? -eq 0 ]; then
        echo "Mount success!"
    else
        echo "Something went wrong with the mount..."
    fi
fi

Answer 1

您使用 grep 将返回任何包含字符串 /myfilesystem 的挂载点...例如:这两个:

• /myfilesystem
• /home/james/myfilesystem

更喜欢使用像下面这样更规范的东西:

mountpoint -q "${MOUNTPOINT}"

您可以使用 [ 来测试路径是否为目录:

if [ ! -d "${MOUNTPOINT}" ]; then
    if [ -e "${MOUNTPOINT}" ]; then
        echo "Mountpoint exists, but isn't a directory..."
    else
        echo "Mountpoint doesn't exist..."
    fi
fi

mkdir -p 将根据需要创建所有父目录:

mkdir -p "${MOUNTPOINT}"

最后，通过利用 bash 的变量扩展来测试目录是否为空:

[ "$(echo ${MOUNTPOINT}/*)" != "${MOUNTPOINT}/*" ]

以一定程度的“安全”运行脚本也是一个好主意。查看 set 内置命令:https://linux.die.net/man/1/bash

-e      Exit immediately if a pipeline (which may consist of a single simple command), a
        list, or a compound command (see SHELL GRAMMAR above), exits with a non-zero
        status.
-u      Treat unset variables and parameters other than the special parameters "@" and "*"
        as an error when performing parameter expansion.

完整:(注意 bash -eu)

#!/bin/bash -eu

MOUNTPOINT="/myfilesystem"

if [ ! -d "${MOUNTPOINT}" ]; then
    if [ -e "${MOUNTPOINT}" ]; then
        echo "Mountpoint exists, but isn't a directory..."
        exit 1
    fi
    mkdir -p "${MOUNTPOINT}"
fi

if [ "$(echo ${MOUNTPOINT}/*)" != "${MOUNTPOINT}/*" ]; then
    echo "Mountpoint is not empty!"
    exit 1
fi

if mountpoint -q "${MOUNTPOINT}"; then
    echo "Already mounted..."
    exit 0
fi

mount "${MOUNTPOINT}"
RET=$?
if [ ${RET} -ne 0 ]; then
    echo "Mount failed... ${RET}"
    exit 1
fi

echo "Mounted successfully!"
exit 0