如何在Bash脚本中使用Expect生成预填充的终端会话

Question

I asked a slightly different version of this a few months back and never got it to work properly, this question has moved on a bit and has new code blocks.

When I log onto my assorted PCs I usually have a number of things I want to happen automatically, but not always straight away.

These include starting terminal sessions in specific locations on specific workspaces (because you get used to using the same layout) and those terminal sessions performing specific acts such as ssh commands (I DO NOT want to embed passwords into the script in any way or piped, just want to populate the command into terminal session so that when I eventually get to that specific terminal session I just need to hit enter).

However sometimes when you logon after a reboot you may not want to execute those commands immediately as a higher priority action may need your attention first.

So....what I want is my login script to open terminal sessions and have session commands for that specific terminal session pre populated on the command line, but not yet executed.

I use Mate and Compiz as my DE as I like its flexibility.

At the moment my bash script looks life this.

#!/bin/bash

# This script is to open a number of windows at specific locations and execute startup commands in those windows.
# It's designed to save time on a new boot up environment and keep the environment consistent.


# Define function to see which ViewPort we are currently on



CurrentViewportQuery () {

TOTALAREA=`wmctrl -d | awk '{print $4}' | awk -F'x' '{print $1}'`

VPAREA=`wmctrl -d | awk '{print $9}' | awk -F'x' '{print $1}'`

CURRENTVPORTREF=`wmctrl -d | awk '{print $6}' | awk -F',' '{print $1}'`

TOTALVPORTS=`echo "$TOTALAREA/$VPAREA" | bc`

CURRENTVPORT=`echo "($CURRENTVPORTREF/$VPAREA)+1" | bc`

 }

# TerminalSessionTargets () {



CurrentViewportQuery

#  echo "totalarea $TOTALAREA vparea $VPAREA currentvportref $CURRENTVPORTREF totalvports $TOTALVPORTS currentvport $CURRENTVPORT"

#  exit 99 # Debug Exit Point

# The following sleep is to allow compiz to fire up fully before we open the terminal sessions or else compositing isn't enabled when the terminal sessions open leading to time based inconsistencies.

sleep 3

#  The following defines the number of terminal session I want for this version of the script, the location onscreen and the target IP address for the ssh session
# In this instance 9 terminal sessions spread over 3 workspaces starting at workspace 3 (this version of the script runs on a machine with a 4k screen)

TERM[0]="24"
TERMLOC[0]="180+400"
TERM[1]="25"
TERMLOC[1]="1305+400"
TERM[2]="xxx"
TERMLOC[2]="2430+400"
TERM[3]="112"
TERMLOC[3]="180+400"
TERM[4]="117"
TERMLOC[4]="1305+400"
TERM[5]="xxx"
TERMLOC[5]="2430+400"
TERM[6]="191"
TERMLOC[6]="180+400"
TERM[7]="193"
TERMLOC[7]="1305+400"
TERM[8]="xxx"
TERMLOC[8]="2430+400"


STARTTERM="0"

FIRSTTARGETVPORT="3"
# FIRSTTARGETVPORT="5"  #  Temp line for code testing  
LASTTARGETVPORT=$((TOTALVPORTS))
NUMBEROFTARGETVPORTS=$((TOTALVPORTS-(FIRSTTARGETVPORT-1)))
NUMBERTERMSPERVPORT=$((${#TERM[*]}/NUMBEROFTARGETVPORTS))

echo "last targetvport $LASTTARGETVPORT numbertargetvports $NUMBEROFTARGETVPORTS termspervport $NUMBERTERMSPERVPORT"  #  Debug output so I can confirm location of spawned terminal session


# Turn off touch sensitive screen

SCREENVALUE=`xinput | grep 'Touchscreen' | cut -f 2 | sed 's/id=//'`

xinput --set-prop $SCREENVALUE 'Device Enabled' 0

# exit

# First lets calculate how many workspaces we have on this machine

CurrentViewportQuery

# Now the dimensions of each viewport

for ((i=1;$i<=$(($TOTALAREA / $VPAREA));i++)); do
VPORT[$i]=$(($VPAREA * ($i-1))) #sets the array entry at index $i to the next viewsize. Remember that $i increases by one every loop

done

#  Now lets open the sshdesktops desktops in viewport 3

FIRSTVPORTTERM="$STARTTERM"

let LASTVPORTTERM="$STARTTERM+($NUMBERTERMSPERVPORT-1)"  # The -1 is to make sure the first term which is number 0 is included

for NEXTTARGETVPORT in `eval echo {$FIRSTTARGETVPORT..$LASTTARGETVPORT}`; do

echo "targetvport ${NEXTTARGETVPORT}"

wmctrl -o ${VPORT[NEXTTARGETVPORT]},0

until [ $CURRENTVPORT -eq $NEXTTARGETVPORT ]; do

CurrentViewportQuery

done

for THISVPORTSTERMS in `eval echo {$FIRSTVPORTTERM..$LASTVPORTTERM}`; do


expect -c " spawn -noecho mate-terminal --window-with-profile=default --geometry=85x24+${TERMLOC[THISVPORTSTERMS]} --title='SSH${TERM[THISVPORTSTERMS]}';
expect \">:\";
send \"ssh root@192.168.12.${TERM[THISVPORTSTERMS]}\";
interact;
expect eof;"

done

Now the script runs fine in terms of identifying the workspaces correctly, switching to the correct workspace and the expect -c command near the bottom of the code block is spawning the mate-terminal session at the correct location on each workspace, however it's not populating the terminal session with the required ssh command (basically the send \\"ssh@192.168......" bit isn't working).

I've tried various syntax versions and revisited this now a few times when I've had a few minutes on my hands....but so far no joy so am back here asking again.

Answer 1

It would help if you reduced your examples to the minimum necessary. In your case the problem is that when you spawn mate-terminal , expect creates a pseudo-tty pty between it and the command, but then mate-terminal creates another pty and runs the shell in it. So your send command is sent to something that is going to ignore it.

What you need to do is, for example, run the expect command inside the mate-terminal as in:

mate-terminal -x expect -c 'spawn bash -i; send "echo hello";interact'

This is still a little inefficient as we still have two pty's. So an alternative is to use the ioctl TIOCSTI which can push characters onto the input of a pty. Write a simple perl script, pushtype with

#!/usr/bin/perl
# push characters onto tty input queue as if typed
# see man tty_ioctl. https://stackoverflow.com/a/45130404/5008284
use strict;
require 'sys/ioctl.ph';
foreach my $ch (split('',join(" ",@ARGV))){
  ioctl(STDOUT, &TIOCSTI, $ch) or die $!;
}

and then you can do use

mate-terminal -x bash -c 'pushtype "echo hello"; exec bash -i'

and you will have the echo hello ready in the input of your shell, with no need for another pty.