Verify a file exists over ssh

Question

I am trying to test if a file exists over SSH using pexpect. I have got most of the code working but I need to catch the value so I can assert whether the file exists. The code I have done is below:

def VersionID():

        ssh_newkey = 'Are you sure you want to continue connecting'
        # my ssh command line
        p=pexpect.spawn('ssh [email protected]')

        i=p.expect([ssh_newkey,'password:',pexpect.EOF])
        if i==0:
            p.sendline('yes')
            i=p.expect([ssh_newkey,'password:',pexpect.EOF])
        if i==1:
            p.sendline("word")
            i=p.expect('service@main-:')
            p.sendline("cd /opt/ad/bin")
            i=p.expect('service@main-:')
            p.sendline('[ -f email_tidyup.sh ] && echo "File exists" || echo "File does not exists"')
            i=p.expect('File Exists')
            i=p.expect('service@main-:')
            assert True
        elif i==2:
            print "I either got key or connection timeout"
            assert False

        results = p.before # print out the result

VersionID()

Thanks for any help.

Answer 1

Why not take advantage of the fact that the return code of the command is passed back over SSH?

$ ssh victory 'test -f .bash_history'
$ echo $?
0
$ ssh victory 'test -f .csh_history'
$ echo $?
1
$ ssh hostdoesntexist 'test -f .csh_history'
ssh: Could not resolve hostname hostdoesntexist: Name or service not known
$ echo $?
255

This way, you can just check the return code without needing to capture output.