Bash：语法错误：重定向意外
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Bash: Syntax error: redirection unexpected
提问by Open the way
I do this in a script:
我在脚本中执行此操作：
read direc <<< $(basename `pwd`)
and I get:
我得到：
Syntax error: redirection unexpected
in an ubuntu machine
在 ubuntu 机器上
/bin/bash --version
GNU bash, version 4.0.33(1)-release (x86_64-pc-linux-gnu)
while I do not get this error in another suse machine:
虽然我在另一台 suse 机器上没有收到此错误：
/bin/bash --version
GNU bash, version 3.2.39(1)-release (x86_64-suse-linux-gnu)
Copyright (C) 2007 Free Software Foundation, Inc.
Why the error?
为什么会出错？
回答by John Kugelman
Does your script reference /bin/bashor /bin/shin its hash bang line? The default system shell in Ubuntu is dash, not bash, so if you have #!/bin/shthen your script will be using a different shell than you expect. Dash does not have the <<<redirection operator.
您的脚本是否引用/bin/bash或/bin/sh在其散列行中？Ubuntu 中的默认系统 shell 是dash，而不是bash，因此如果您有，#!/bin/sh那么您的脚本将使用与您预期不同的 shell。Dash 没有<<<重定向操作符。
回答by kemicofa ghost
Docker:
码头工人：
I was getting this problem from my Dockerfile as I had:
我从我的 Dockerfile 中遇到了这个问题：
RUN bash < <(curl -s -S -L https://raw.githubusercontent.com/moovweb/gvm/master/binscripts/gvm-installer)
However, according to this issue, it was solved:
但是，根据这个问题，它被解决了：
The execform makes it possible to avoid shell string munging, and to
RUNcommands using a base image that does not contain/bin/sh.Note
To use a different shell, other than
/bin/sh, use the execform passing in the desired shell. For example,RUN ["/bin/bash", "-c", "echo hello"]
在EXEC形式使得能够避免壳串改写（munging），并
RUN使用不包含基础图像的命令/bin/sh。笔记
要使用除 之外的其他外壳程序，请
/bin/sh使用传入所需外壳程序的exec形式。例如，RUN ["/bin/bash", "-c", "echo hello"]
Solution:
解决方案：
RUN ["/bin/bash", "-c", "bash < <(curl -s -S -L https://raw.githubusercontent.com/moovweb/gvm/master/binscripts/gvm-installer)"]
Notice the quotes around eachparameter.
注意每个参数周围的引号。
回答by Chris Pietschmann
If you're using the following to run your script:
如果您使用以下内容来运行您的脚本：
sudo sh ./script.sh
Then you'll want to use the following instead:
然后，您将需要使用以下内容：
sudo bash ./script.sh
The reason for this is that Bash is not the default shell for Ubuntu. So, if you use "sh" then it will just use the default shell; which is actually Dash. This will happen regardless if you have #!/bin/bashat the top of your script. As a result, you will need to explicitly specify to use bashas shown above, and your script should run at expected.
原因是 Bash 不是 Ubuntu 的默认 shell。所以，如果你使用“sh”，那么它只会使用默认的 shell；这实际上是 Dash。无论您是否#!/bin/bash在脚本的顶部，这都会发生。因此，您需要明确指定使用bash如上所示，并且您的脚本应按预期运行。
Dash doesn't support redirects the same as Bash.
Dash 不支持与 Bash 相同的重定向。
回答by AmirHossein
You can get the output of that command and put it in a variable. then use heredoc. for example:
您可以获取该命令的输出并将其放入变量中。然后使用heredoc. 例如：
nc -l -p 80 <<< "tested like a charm";
can be written like:
可以写成：
nc -l -p 80 <<EOF
tested like a charm
EOF
and like this (this is what you want):
像这样（这就是你想要的）：
text="tested like a charm"
nc -l -p 80 <<EOF
$text
EOF
Practical example in busyboxunder dockercontainer:
容器busybox下的实际示例docker：
kasra@ubuntu:~$ docker run --rm -it busybox
/ # nc -l -p 80 <<< "tested like a charm";
sh: syntax error: unexpected redirection
/ # nc -l -p 80 <<EOL
> tested like a charm
> EOL
^Cpunt! => socket listening, no errors. ^Cpunt! is result of CTRL+C signal.
/ # text="tested like a charm"
/ # nc -l -p 80 <<EOF
> $text
> EOF
^Cpunt!
回答by ghostdog74
do it the simpler way,
用更简单的方法做，
direc=$(basename `pwd`)
Or use the shell
或者使用外壳
$ direc=${PWD##*/}
回答by Motin
Another reason to the error may be if you are running a cron job that updates a subversion working copy and then has attempted to run a versioned script that was in a conflicted state after the update...
错误的另一个原因可能是，如果您正在运行更新 subversion 工作副本的 cron 作业，然后尝试运行更新后处于冲突状态的版本化脚本...
回答by Michael Mather
On my machine, if I run a script directly, the default is bash.
在我的机器上，如果我直接运行脚本，默认是bash.
If I run it with sudo, the default is sh.
如果我用 运行它sudo，默认是sh.
That's why I was hitting this problem when I used sudo.
这就是为什么我在使用sudo.
回答by Sijeesh
Before running the script, you should check first line of the shell script for the interpreter.
在运行脚本之前，您应该检查解释器的 shell 脚本的第一行。
Eg: if scripts starts with /bin/bash , run the script using the below command "bash script_name.sh"
例如：如果脚本以 /bin/bash 开头，请使用以下命令“bash script_name.sh”运行脚本
if script starts with /bin/sh, run the script using the below command "sh script_name.sh"
如果脚本以 /bin/sh 开头，请使用以下命令“sh script_name.sh”运行脚本
./sample.sh - This will detect the interpreter from the first line of the script and run.
./sample.sh - 这将从脚本的第一行检测解释器并运行。
Different Linux distributions having different shells as default.
不同的 Linux 发行版具有不同的默认 shell。
回答by Mansur Ali
In my case error is because i have put ">>" twice
在我的情况下，错误是因为我已经把“>>”两次
mongodump --db=$DB_NAME --collection=$col --out=$BACKUP_LOCATION/$DB_NAME-$BACKUP_DATE >> >> $LOG_PATH
i just correct it as
我只是将其更正为
mongodump --db=$DB_NAME --collection=$col --out=$BACKUP_LOCATION/$DB_NAME-$BACKUP_DATE >> $LOG_PATH
