尝试ssh -t -t(或简称ssh -tt)强制伪tty分配，即使stdin不是终端。

请参见:终止bash脚本执行的SSH会话

从ssh manpage:

-T      Disable pseudo-tty allocation.

-t      Force pseudo-tty allocation.  This can be used to execute arbitrary 
        screen-based programs on a remote machine, which can be very useful,
        e.g. when implementing menu services.  Multiple -t options force tty
        allocation, even if ssh has no local tty.

在看了很多这样的答案之后，我想分享一下我的解决方案。我只是在heredoc之前添加了/bin/bash，它不再给出错误了。

用这个:

ssh user@machine /bin/bash <<'ENDSSH'
   hostname
ENDSSH

而不是这个(给出错误):

ssh user@machine <<'ENDSSH'
   hostname
ENDSSH

或者用这个:

ssh user@machine /bin/bash < run-command.sh

而不是这个(给出错误):

ssh user@machine < run-command.sh

额外的:

如果你仍然需要一个远程交互式提示，例如，如果你正在远程运行的脚本提示你输入密码或其他信息，因为前面的解决方案不允许你输入提示。

ssh -t user@machine "$(<run-command.sh)"

如果你还想把整个会话记录在一个文件logfile.log中:

ssh -t user@machine "$(<run-command.sh)" | tee -a logfile.log

尝试ssh -t -t(或简称ssh -tt)强制伪tty分配，即使stdin不是终端。

请参见:终止bash脚本执行的SSH会话

从ssh manpage:

-T      Disable pseudo-tty allocation.

-t      Force pseudo-tty allocation.  This can be used to execute arbitrary 
        screen-based programs on a remote machine, which can be very useful,
        e.g. when implementing menu services.  Multiple -t options force tty
        allocation, even if ssh has no local tty.

The warning message Pseudo-terminal will not be allocated because stdin is not a terminal. is due to the fact that no command is specified for ssh while stdin is redirected from a here document. Due to the lack of a specified command as an argument ssh first expects an interactive login session (which would require the allocation of a pty on the remote host) but then has to realize that its local stdin is no tty/pty. Redirecting ssh's stdin from a here document normally requires a command (such as /bin/sh) to be specified as an argument to ssh - and in such a case no pty will be allocated on the remote host by default.

由于通过ssh执行的命令不需要tty/pty(如vim或top)，所以切换到ssh的-t是多余的。 只需使用ssh -T user@server <<EOT…或ssh user@server /bin/bash <<EOT…警告就会消失。

如果<<EOF没有转义或单引号(即<<\EOT或<<'EOT')，这里文档中的变量将在执行ssh ....之前由本地shell展开结果是，这里文档中的变量将保持为空，因为它们仅在远程shell中定义。

因此，如果$REL_DIR既可以被本地shell访问，又可以在远程shell中定义，那么$REL_DIR必须在ssh命令(下面的版本1)之前在here文档之外定义;或者，如果使用<<\EOT或<<'EOT'，如果ssh命令对stdout的唯一输出是由转义/单引号here文档中的echo "$REL_DIR"生成的，则ssh命令的输出可以分配给REL_DIR(下面的版本2)。

第三种方法是将here文档存储在一个变量中，然后将该变量作为命令参数传递给ssh -t user@server "$heredoc"(下面是第3版)。

最后但并非最不重要的是，检查远程主机上的目录是否已成功创建(参见:使用ssh检查远程主机上是否存在文件)也不是一个坏主意。

# version 1

unset DEP_ROOT REL_DIR
DEP_ROOT='/tmp'
datestamp=$(date +%Y%m%d%H%M%S)
REL_DIR="${DEP_ROOT}/${datestamp}"

ssh localhost /bin/bash <<EOF
if [ ! -d "$DEP_ROOT" ] && [ ! -e "$DEP_ROOT" ]; then
   echo "creating the root directory" 1>&2
   mkdir "$DEP_ROOT"
fi
mkdir "$REL_DIR"
#echo "$REL_DIR"
exit
EOF

scp -r ./dir1 user@server:"$REL_DIR"
scp -r ./dir2 user@server:"$REL_DIR"


# version 2

REL_DIR="$(
ssh localhost /bin/bash <<\EOF
DEP_ROOT='/tmp'
datestamp=$(date +%Y%m%d%H%M%S)
REL_DIR="${DEP_ROOT}/${datestamp}"
if [ ! -d "$DEP_ROOT" ] && [ ! -e "$DEP_ROOT" ]; then
   echo "creating the root directory" 1>&2
   mkdir "$DEP_ROOT"
fi
mkdir "$REL_DIR"
echo "$REL_DIR"
exit
EOF
)"

scp -r ./dir1 user@server:"$REL_DIR"
scp -r ./dir2 user@server:"$REL_DIR"


# version 3

heredoc="$(cat <<'EOF'
# -onlcr: prevent the terminal from converting bare line feeds to carriage return/line feed pairs
stty -echo -onlcr
DEP_ROOT='/tmp'
datestamp="$(date +%Y%m%d%H%M%S)"
REL_DIR="${DEP_ROOT}/${datestamp}"
if [ ! -d "$DEP_ROOT" ] && [ ! -e "$DEP_ROOT" ]; then
   echo "creating the root directory" 1>&2
   mkdir "$DEP_ROOT"
fi
mkdir "$REL_DIR"
echo "$REL_DIR"
stty echo onlcr
exit
EOF
)"

REL_DIR="$(ssh -t localhost "$heredoc")"

scp -r ./dir1 user@server:"$REL_DIR"
scp -r ./dir2 user@server:"$REL_DIR"

所有相关信息都在现有的答案中，但让我尝试一个实用的总结:

tl; diana:

使用命令行参数传递命令: SSH jdoe@server“…” “…'字符串可以跨越多行，所以即使不使用here-document，你也可以保持代码的可读性: SSH jdoe@server“…” 不要通过stdin传递命令，就像你使用here-document一样: ssh jdoe@server <<'EOF' #不这样做…EOF

将命令作为参数传递，按原样工作，并且:

伪终端的问题甚至不会出现。 您不需要在命令末尾使用退出语句，因为会话将在处理完命令后自动退出。

简而言之:通过stdin传递命令是一种与ssh的设计不一致的机制，并且会导致必须解决的问题。 如果你想了解更多，请继续阅读。

可选背景信息:

Ssh接受在目标服务器上执行的命令的机制是一个命令行参数:最后一个操作数(非选项参数)接受一个包含一个或多个shell命令的字符串。

By default, these commands run unattended, in a non-interactive shell, without the use of a (pseudo) terminal (option -T is implied), and the session automatically ends when the last command finishes processing. In the event that your commands require user interaction, such as responding to an interactive prompt, you can explicitly request the creation of a pty (pseudo-tty), a pseudo terminal, that enables interacting with the remote session, using the -t option; e.g.: ssh -t jdoe@server 'read -p "Enter something: "; echo "Entered: [$REPLY]"' Note that the interactive read prompt only works correctly with a pty, so the -t option is needed. Using a pty has a notable side effect: stdout and stderr are combined and both reported via stdout; in other words: you lose the distinction between regular and error output; e.g.: ssh jdoe@server 'echo out; echo err >&2' # OK - stdout and stderr separate ssh -t jdoe@server 'echo out; echo err >&2' # !! stdout + stderr -> stdout

如果没有这个参数，ssh会创建一个交互式shell——包括当你通过stdin发送命令时，这就是问题开始的地方:

For an interactive shell, ssh normally allocates a pty (pseudo-terminal) by default, except if its stdin is not connected to a (real) terminal. Sending commands via stdin means that ssh's stdin is no longer connected to a terminal, so no pty is created, and ssh warns you accordingly: Pseudo-terminal will not be allocated because stdin is not a terminal. Even the -t option, whose express purpose is to request creation of a pty, is not enough in this case: you'll get the same warning. Somewhat curiously, you must then double the -t option to force creation of a pty: ssh -t -t ... or ssh -tt ... shows that you really, really mean it. Perhaps the rationale for requiring this very deliberate step is that things may not work as expected. For instance, on macOS 10.12, the apparent equivalent of the above command, providing the commands via stdin and using -tt, does not work properly; the session gets stuck after responding to the read prompt: ssh -tt jdoe@server <<<'read -p "Enter something: "; echo "Entered: [$REPLY]"'

在不太可能发生的情况下，您想要作为参数传递的命令使命令行对您的系统来说太长(如果它的长度接近getconf ARG_MAX -请参阅本文)，请考虑先以脚本的形式将代码复制到远程系统(例如，使用scp)，然后发送命令来执行该脚本。

在紧急情况下，使用-T，并通过stdin提供命令，后面有一个退出命令，但请注意，如果您还需要交互功能，则使用-tt代替-T可能不起作用。

我添加这个答案是因为它解决了与我遇到的相同错误消息相关的问题。

问题:我在Windows下安装了cygwin，并得到这个错误:伪终端将不会被分配，因为stdin不是终端

解决方案:原来我没有安装openssh客户端程序和实用程序。正因为如此，cygwin使用的是ssh的Windows实现，而不是cygwin版本。解决方案是安装openssh cygwin包。