如何在bash中显示一行文本

Question

在bash中执行代码时，我试图仅显示一行文本。 例如，如果我要运行以下命令

./myscript.sh /etc 

它会在我的脚本EX中显示所有行：

/etc is a directory
etc/hosts is a file
/dev/tty0 is a character device
/dev/sda is a block device
/MyNonExistantDirectory is not a file, directory, character device or block device on your system.

我要显示的是

/etc is a directory

在使用命令./myscript.sh /etc 。

#!/bin/bash
device0="/etc"
if [ -d "$device0" ]
then
echo "$device0 is a directory."
fi

device1="/etc/hosts"
if [ -f "$device1" ]
then
echo "$device1 is a file."
fi

device2="/dev/tty0"
if [ -c "$device2" ]
then
echo "$device2 is a character device."
fi

device3="/dev/sda"
if [ -b "$device3" ]
then
echo "$device3 is a block device."
fi

device4="/MyNonExistantDirectory"
if [ -f "$device4" ]
then
echo "$device4 is not a file, directory, character device or block device on your system."
fi

Answer 1

使用$1来获取参数。 并使用if/elif/else测试互斥条件。

#!/bin/bash
device=$1
if [ -d "$device" ]
then
    echo "$device is a directory."
elif [ -f "$device" ]
then
    echo "$device is a file."
elif [ -c "$device" ]
then
    echo "$device is a character device."
elif [ -b "$device" ]
then
    echo "$device is a block device."
else
    echo "$device is not a file, directory, character device or block device on your system."
fi

Answer 2

我想，您几乎钉牢了它； 您要做的就是从第一个位置参数（$ 1）中创建一个“设备”，然后将每个路径的if语句转换为带有elif子句的单个if语句。

#!/bin/bash
device=$1

if [ -d "$device" ]; then
    echo "$device is a directory."

elif [ -f $device ]; then
    echo "$device1 is a file."

elif [ -c $device ]; then
    echo "$device2 is a character device."

elif [ -b $device ]; then
    echo "$device3 is a block device."

else
    echo "$device is not a file, directory, character device or block device on your system."

fi

Answer 3

linux命令头将显示文件的顶行。 因此

head -1 

我相信会产生您想要的输出。