linux if 逻辑运算符

# 检查文件是否存在且可读
if [ -f "/path/to/file" ] && [ -r "/path/to/file" ]; then
    echo "File exists and is readable."
else
    echo "File does not exist or is not readable."
fi

# 检查变量是否为空或未设置
if [ -z "$VAR" ] || [ -v VAR ]; then
    echo "Variable is empty or not set."
else
    echo "Variable is set and not empty."
fi

# 检查文件是否存在，如果不存在则创建它
if [ ! -f "/path/to/file" ]; then
    touch "/path/to/file"
    echo "File created."
else
    echo "File already exists."
fi

echo "Checking if file exists and is writable..."
if [ -f "/path/to/file" ] && [ -w "/path/to/file" ]; then
    echo "File exists and is writable."
else
    echo "File does not exist or is not writable."
fi