bash - bash setid 和读取冻结

Question

我有用于 ssh 登录的脚本，而不是期望：

function do_auth_connect(){
    if [ -n "$SSH_ASKPASS_TMPFILE" ]; then
        cat "$SSH_ASKPASS_TMPFILE"
        exit 0
    elif [ $# -lt 1 ]; then
        echo "Usage: echo password | $0 <ssh command line options>" >&2
        exit 1
    fi

    sighandler() {
        rm "$TMP_PWD"
    }

    TMP_PWD=$(mktemp)
    chmod 600 "$TMP_PWD"
    trap 'sighandler' SIGHUP SIGINT SIGQUIT SIGABRT SIGKILL SIGALRM SIGTERM

    export SSH_ASKPASS=$0
    export SSH_ASKPASS_TMPFILE=$TMP_PWD

    [ "$DISPLAY" ] || export DISPLAY=dummydisplay:0
    read password
    echo $password >> "$TMP_PWD"

    # use setsid to detach from tty
    #exec setsid "$@"
    setsid "$@"

    rm "$TMP_PWD"
}

如果我使用如下命令：

echo "my_password" | do_auth_connect ssh use@domain "uname -a"

一切正常。但如果我使用：

read password
echo "$password" | do_auth_connect ssh use@domain "uname -a"

脚本冻结。

“set -x”表示脚本进入循环，并等待另一个“读取”参数。

我该如何解决这个问题？谢谢

---UPD---（对于@Barmar）

正常时设置 -x 输出（以 scp 为例）：

+ echo 'user_password'
+ do_auth_connect scp -P 444 user@domain:/home/user/dbg.log /home/user/dbg.log
+ '[' -n '' ']'
+ '[' 5 -lt 1 ']'
++ mktemp
+ TMP_PWD=/tmp/tmp.X8TKTIchq6
+ chmod 600 /tmp/tmp.X8TKTIchq6
+ trap sighandler SIGHUP SIGINT SIGQUIT SIGABRT SIGKILL SIGALRM SIGTERM
+ export SSH_ASKPASS=./1.sh
+ SSH_ASKPASS=./1.sh
+ export SSH_ASKPASS_TMPFILE=/tmp/tmp.X8TKTIchq6
+ SSH_ASKPASS_TMPFILE=/tmp/tmp.X8TKTIchq6
+ '[' :0.0 ']'
+ read password
+ echo 'user_password'
+ setsid scp -P 444 user@domain:/home/user/dbg.log /home/user/dbg.log
+ echo 'user_password'
+ do_auth_connect scp -P 444 user@domain:/home/user/dbg.log /home/user/dbg.log
+ '[' -n /tmp/tmp.X8TKTIchq6 ']'
+ cat /tmp/tmp.X8TKTIchq6
+ exit 0
+ rm /tmp/tmp.X8TKTIchq6
+ exit

失败时：

+ read pass
> user_password
+ echo 'user_password'
+ do_auth_connect scp -P 444 user@domain:/home/user/dbg.log /home/user/dbg.log
+ '[' -n '' ']'
+ '[' 5 -lt 1 ']'
++ mktemp
+ TMP_PWD=/tmp/tmp.7usdmtHgqt
+ chmod 600 /tmp/tmp.7usdmtHgqt
+ trap sighandler SIGHUP SIGINT SIGQUIT SIGABRT SIGKILL SIGALRM SIGTERM
+ export SSH_ASKPASS=./1.sh
+ SSH_ASKPASS=./1.sh
+ export SSH_ASKPASS_TMPFILE=/tmp/tmp.7usdmtHgqt
+ SSH_ASKPASS_TMPFILE=/tmp/tmp.7usdmtHgqt
+ '[' :0.0 ']'
+ read password
+ echo 'user_password'
+ setsid scp -P 444 user@domain:/home/user/dbg.log /home/user/dbg.log
+ read -p '> ' pass

这就是全部，^C 不起作用:)

---UPD2---

我发现任何“读取”都会破坏脚本例如：

read null
echo "user_password" | do_auth_connect scp -P 444 user@domain:/home/user/dbg.log ~/dbg.log

有一些冻结问题

score 0 · Accepted Answer

来到这里寻找类似的情况：ssh 调用包含调用的远程脚本setsid，并且观察 ssh 永远不会终止。

ssh remotehost start-daemon.sh

在哪里启动-daemon.sh

#!/bin/bash
...
setsid $daemon $args &
exit 0

ssh 将挂起，必须给予 ^C 才能停止。修复（如https://serverfault.com/questions/364689评论中所暗示的）是重定向 setid 的标准输出：

setsid $daemon $args > /dev/null &

然后 ssh 按预期停止。在我的测试中，stderr 不需要相同的处理。

score 0 · Accepted Answer

SSH_ASKPASS           If ssh needs a passphrase, it will read the passphrase from
                       the current terminal if it was run from a terminal.  If ssh
                       does not have a terminal associated with it but DISPLAY and
                       SSH_ASKPASS are set, it will execute the program specified by
                       SSH_ASKPASS and open an X11 window to read the passphrase.
                       This is particularly useful when calling ssh from a .xsession
                       or related script.  (Note that on some machines it may be
                       necessary to redirect the input from /dev/null to make this
                       work.)

bash - bash setid 和读取冻结

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