期望脚本读取空行

Question

我有一个 IP 列表，我正在循环通过 ssh 进入每个 IP 并捕获一些日志。目前，它将遍历所有 IP 并执行我想要的操作，当它到达最后一个 IP 时会出现问题，在完成最后一行后，它会尝试生成另一个空行，从而导致错误。 (spawn ssh root@)

如何防止此错误发生？

我的期望.sh

set user user
set pass pass
set timeout 600

# Get the list of hosts, one per line #####
set f [open "/my/ip/list.txt"]
set hosts [split [read $f] "\n"]
close $f

# Iterate over the hosts
foreach host $hosts {
    spawn ssh $user@$host
    expect {
            "connecting (yes/no)? " {send "yes\r"; exp_continue}
            "assword: " {send "$pass\r"}
    }

    expect "# "
    send "myscript.sh -x\r"
    expect "# "
    send "exit\r"
    expect eof
}

myiplist.txt

172.17.255.255
172.17.255.254
...

错误：

[root@172.17.255.255: ]# exit  //last ip in the list
Connection to 172.17.255.255 closed.
spawn ssh root@
ssh: Could not resolve hostname : Name or service not known
expect: spawn id exp5 not open

Answer 1

文本文件以换行符结尾

first line\n
...
last line\n

因此，当您将整个文件读入一个变量，然后按换行符拆分时，您的列表如下所示：

{first line} {...} {last line} {}

因为最后一个换行符后面有一个空字符串。

在 Tcl/expect 中迭代文件行的惯用方法是：

set f [open file r]
while {[gets $f host] != -1} {
    do something with $host
}
close $f

或者，使用the read command 的-nonewline 选项

set f [open file]
set hosts [split [read -nonewline $f] \n]
close $f
foreach host $hosts {...}