ssh echo

[vinuk23]

hi,
Can I use a popen to ssh a command to another box and then use a Unix echo command to print output to my present console..?

like this

char exe[]="\/usr\/bin\/ssh -v HOSTNAME \";perl -e 'print \" Hello world \"' ";

Thnk u,

[matsp]

sure, just send "ssh machine echo \"Hello, World\"" to the machine.

You don't need to do \/ - only \ needs an extra \.


--
Mats

[vinuk23]

I tried the simple echo command first but its not working...some how the echo doesnt diosplay on present console.

char exe[]="\/usr\/bin\/ssh -v HOSTNAME  \" ;echo \" Hello world \"  \" ";

Doesnt work even now....

[matsp]

Describe what happens...

And you still have unnecessary backslashes in your string - it probably doesn't matter, but it tells me you didn't read my post very well.

--
Mats

[vinuk23]

Hi like I was saying I tried without the qoutes too....
Actually this is what I am trying.....

char exe[]="\/usr\/bin\/ssh -v HOSTNAME \";echo printing file ; ls -ltr  ";

As I showed above....I get the list of files from the other box....
But I dont get the echo output.....
any idea what I am missing..../

[matsp]

Not sure I understand what you are saying: Are you saying you get the result of ls, but not from echo, or are you saying that you get the result of ls on the local machine, and no result from ssh?

What happens if you just do

ssh hostname echo Hello World

on a command line?

--
Mats

[vinuk23]

At the same time if I run this command from the command line ....

ssh hostname echo Hello World

It get the reply back as 'Hello world'


"...Are you saying you get the result of ls, but not from echo..."
As you said....I get the result of the ls...but not from echo.

[matsp]

And what do you get if you do:

char exe[]="/usr/bin/ssh HOSTNAME  echo \"Hello world \" ";

and pass "exe" to system()?


--
Mats

[vinuk23]

 char cmd[400];

sprintf(cmd,"\/usr\/bin\/ssh -v HOSTNAME \";echo printing file ; ls -ltr  ";);
char exe_str[]=system( cmd );
 if((ptr = popen(exe_str, "r")) == NULL)
perror("Couldn't open pipe");
 if(fgets(data, 256, ptr) == NULL)
{
 }
 pclose(alp);

while (fgets(data, 100, ptr) != NULL)
 {
printf("%s ",line);
}

I get the echo output now.
But I have a new problem....
I get the system( cmd) ; output on the console even before the printf command in the fgets statement....

(please let me know if I was clear)

[vart]

I get the system( cmd) ; output on the console even before the printf command in the fgets statement....

(please let me know if I was clear)

Not really.

And why do you still continue to use the ptr is it is NULL. Shouldn't you exit your function?

[matsp]

Really, you do have to CHOOSE whether you want to use popen or system - not both. Also, you should get a warning for "converting integer to string" for the system line in this snippet

char exe_str[]=system( cmd );
 if((ptr = popen(exe_str, "r")) == NULL)

And since exe_str is very unlikely to point to a valid string and the commend executes "OK" [since it is zero -> NULL, it will probably be a NULL pointer, but whatever system returns, it is VERY unlikely to be a valid string pointer in your application]. So popen() either fails or crashes.

--
Mats