bash 在 .bashrc 中回显时 SCP 不起作用？
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SCP doesn't work when echo in .bashrc?
提问by Nehal J Wani
I have two users in Fedora:
我在 Fedora 中有两个用户：
- Wani
- root (quite obvious!)
- 瓦尼
- 根（很明显！）
My contents of .bashrc of user Wani are:
我的用户 Wani .bashrc 的内容是：
# .bashrc
echo "Hello"
# Source global definitions
if [ -f /etc/bashrc ]; then
. /etc/bashrc
fi
# User specific aliases and functions
Now after logging into root, I type the following commands:
现在登录到 root 后，我输入以下命令：
[root@Dell Wani]# touch try.txt
[root@Dell Wani]# service sshd start
[root@Dell Wani]# scp try.txt Wani@localhost:~/
Wani@localhost's password:
Hello
[root@Dell Wani]#
Now I log into Wani, and type:
现在我登录到 Wani，然后输入：
[Wani@Dell ~]$ cat try.txt
cat: try.txt: No such file or directory
[Wani@Dell ~]$
Now I again log into root and type the same command with -v:
现在我再次登录到 root 并使用以下命令键入相同的命令-v：
[root@Dell Wani]# scp -v morph.log Wani@localhost:
Executing: program /usr/bin/ssh host localhost, user Wani, command scp -v -t -- .
OpenSSH_5.6p1, OpenSSL 1.0.0j-fips 10 May 2012
debug1: Reading configuration data /etc/ssh/ssh_config
debug1: Applying options for *
debug1: Connecting to localhost [127.0.0.1] port 22.
debug1: Connection established.
debug1: permanently_set_uid: 0/0
debug1: identity file /root/.ssh/id_rsa type -1
debug1: identity file /root/.ssh/id_rsa-cert type -1
debug1: identity file /root/.ssh/id_dsa type -1
debug1: identity file /root/.ssh/id_dsa-cert type -1
debug1: Remote protocol version 2.0, remote software version OpenSSH_5.6
debug1: match: OpenSSH_5.6 pat OpenSSH*
debug1: Enabling compatibility mode for protocol 2.0
debug1: Local version string SSH-2.0-OpenSSH_5.6
debug1: SSH2_MSG_KEXINIT sent
debug1: SSH2_MSG_KEXINIT received
debug1: kex: server->client aes128-ctr hmac-md5 none
debug1: kex: client->server aes128-ctr hmac-md5 none
debug1: SSH2_MSG_KEX_DH_GEX_REQUEST(1024<1024<8192) sent
debug1: expecting SSH2_MSG_KEX_DH_GEX_GROUP
debug1: SSH2_MSG_KEX_DH_GEX_INIT sent
debug1: expecting SSH2_MSG_KEX_DH_GEX_REPLY
debug1: Host 'localhost' is known and matches the RSA host key.
debug1: Found key in /root/.ssh/known_hosts:2
debug1: ssh_rsa_verify: signature correct
debug1: SSH2_MSG_NEWKEYS sent
debug1: expecting SSH2_MSG_NEWKEYS
debug1: SSH2_MSG_NEWKEYS received
debug1: Roaming not allowed by server
debug1: SSH2_MSG_SERVICE_REQUEST sent
debug1: SSH2_MSG_SERVICE_ACCEPT received
debug1: Authentications that can continue: publickey,gssapi-keyex,gssapi- with-mic,password
debug1: Next authentication method: gssapi-keyex
debug1: No valid Key exchange context
debug1: Next authentication method: gssapi-with-mic
debug1: Unspecified GSS failure. Minor code may provide more information
Credentials cache file '/tmp/krb5cc_0' not found
debug1: Unspecified GSS failure. Minor code may provide more information
Credentials cache file '/tmp/krb5cc_0' not found
debug1: Unspecified GSS failure. Minor code may provide more information
debug1: Unspecified GSS failure. Minor code may provide more information
debug1: Next authentication method: publickey
debug1: Trying private key: /root/.ssh/id_rsa
debug1: Trying private key: /root/.ssh/id_dsa
debug1: Next authentication method: password
Wani@localhost's password:
debug1: Authentication succeeded (password).
Authenticated to localhost ([127.0.0.1]:22).
debug1: channel 0: new [client-session]
debug1: Requesting [email protected]
debug1: Entering interactive session.
debug1: Sending environment.
debug1: Sending env XMODIFIERS = @im=none
debug1: Sending env LANG = en_US.UTF-8
debug1: Sending command: scp -v -t -- .
Hello
[root@Dell Wani]# debug1: client_input_channel_req: channel 0 rtype exit-status reply 0
debug1: channel 0: free: client-session, nchannels 1
debug1: fd 0 clearing O_NONBLOCK
debug1: fd 1 clearing O_NONBLOCK
Transferred: sent 1664, received 1976 bytes, in 0.1 seconds
Bytes per second: sent 22961.5, received 27266.8
debug1: Exit status 0
(And after I press Enter)
（在我按 Enter 之后）
[root@Dell Wani]#
Can anyone please shed some light as to what exactly happened here? Why did the file not get copied to Wani from root?
谁能解释一下这里到底发生了什么？为什么文件没有从 root 复制到 Wani？
采纳答案by nneonneo
Using echoin a .bashrcwill break scp, as scpexpects to see its protocol data over the stdin/stdout channels. See https://bugzilla.redhat.com/show_bug.cgi?id=20527for more discussion on this issue.
使用echoin a .bashrcwill break scp，正如scp预期在 stdin/stdout 通道上看到它的协议数据。有关此问题的更多讨论，请参阅https://bugzilla.redhat.com/show_bug.cgi?id=20527。
There's a few workarounds available:
有一些可用的解决方法：
- Condition on the 'interactive' flag (e.g.
case $- in *i*as suggested by tripleee) - Use the
ttyutility to detect an interactive shell (e.g.if tty > /dev/nullorif [ -t 0 ]) - Check the value of
$SSH_TTY
- 'interactive' 标志的条件（例如，
case $- in *i*如三重奏所建议的那样） - 使用该
tty实用程序检测交互式 shell（例如if tty > /dev/null或if [ -t 0 ]） - 检查值
$SSH_TTY
I suppose you should use whichever one works for you. I don't know what the best (most portable/most reliable) option is, unfortunately.
我想您应该使用适合您的任何一种。不幸的是，我不知道什么是最好的（最便携/最可靠的）选项。
回答by Drew Ogle
To add to nneonneo's options, you can also condition with the interactive flag with
要添加到 nneonneo 的选项，您还可以使用交互式标志进行条件
if [[ $- =~ "i" ]]
which I think is possibly the clearest way in bash.
我认为这可能是 bash 中最清晰的方式。
回答by Manoj Ashok
This works for me,
In .bashrcadd first line as:
这对我有用，
在.bashrc添加第一行：
if [ -z "$PS1" ]; then
return
fi
https://superuser.com/questions/690735/can-i-tell-if-im-in-an-scp-session-in-my-bashrc
https://superuser.com/questions/690735/can-i-tell-if-im-in-an-scp-session-in-my-bashrc
回答by phil294
The defaultUbuntu .bashrccontains the following snippet which already takes care of the problem:
在默认的Ubuntu.bashrc包含下面的代码片段，其已经采取照顾的问题：
# If not running interactively, don't do anything
case $- in
*i*) ;;
*) return;;
esac
回答by bal
In .bashrc, use STDERR as output instead:
在 中.bashrc，使用 STDERR 作为输出：
echo "# Important Notice" >&2
Update: do not use it!We had an issue recently that a (closed source) tool failed due to an echoto STDERR in .bashrc. The tool (using rcp) expected no output at all, neither on STDOUT nor STDERR. And it stuck when it got the echo. Lesson learned: make separate accounts for humans and for machines (scripts), or just stop tattling via .bashrc.
更新：不要使用它！我们最近有一个问题，一个（闭源）工具将失败，因为echo到STDERR在.bashrc。该工具（使用rcp）根本不期望输出，无论是 STDOUT 还是 STDERR。当它得到回声时它就卡住了。经验教训：为人类和机器（脚本）分别建立帐户，或者停止通过.bashrc.
回答by Jambock
The most portable way of testing for an interactive shell seems to be:
测试交互式 shell 的最便携方式似乎是：
test -t 0
if [ $? -eq 0 ]
then
# interactive
;
else
# non-interactive
;
fi
回答by Everett Toews
If you're on Red Hat Enterprise Linux (RHEL) or variant, drop a script that does the echo, or whatever you want, into /etc/profile.d/
如果您使用的是 Red Hat Enterprise Linux (RHEL) 或变体，请将执行echo.
回答by Kishan Sangani
If you want echo statements as well, the from @Blauhirn's answer, you can keep placing your echo statement/s after the case condition.
如果您还需要 echo 语句，来自@Blauhirn 的回答，您可以继续将您的 echo 语句放在 case 条件之后。
case $- in
*i*) ;;
*) return;;
esac
echo "Your Greeting/Warning Message/s here!"
回答by Vijay Padiyar
nneonneo's solution worked for me as well. But since my default shell is TCSH, I had to slightly edit the fix as follows (in .tcshrc):
nneonneo 的解决方案也适用于我。但由于我的默认 shell 是 TCSH，我不得不按如下方式稍微编辑修复程序（在 .tcshrc 中）：
if ( $?SSH_TTY ) then
exec /bin/bash
endif
Just thought I would share for everyone's benefit.
只是想我会为了大家的利益而分享。
