ssh-exec

NAME

SYNOPSIS

ssh-exec [ -b ] -u user@hostname < commands

ssh-exec [ -b ] -u user -t hostname < commands

ssh-exec -p [ -e | -l localuser ] -u user@hostname

ssh-exec -p [ -e | -l localuser ] -u user -t hostname

ssh-exec [ -s | -v ][ -n ][ -b ][ -e | -l localuser ] -u user@hostname < commands

ssh-exec [ -s | -v ][ -n ][ -b ][ -e | -l localuser ] -u user -t hostname < commands

AVAILABILITY

DESCRIPTION

Prior to the remote command invocation it is checked if the remote target system with hostname is up and if it is possible to connect using the provided user to the remote target system.

In addition to the commands it is supported to submit answers to specific outputs (when it is not possible to do it using simple input redirection) or an except(3) script without the need to write extra "wrapper" scripts.

[COMMANDS] Execute commands:

Simple command invocation on a target system:

  ssh-exec -u user@target <<EOM
  ps -ef | grep oracle
  EOM

or

  ssh-exec -u user@target <<EOM
  [COMMANDS]
  ps -ef | grep oracle
  EOM

The [COMMANDS] section keyword is optional as long as it is the first section provided to ssh-exec.

Command invocation with input redirection of needed command inputs:

  ssh-exec -u user@target <<EOM

  restore-data <<EOI
  /dat/backup/acme-001/2020-01-10/etc/hosts
  /etc/hosts
  EOI

  EOM

[ANSWERS] Providing answers to a tty command:

Remote control an interactive command that reads the input from a tty and not from stdin:

  ssh-exec -u user@target <<EOM

  [COMMANDS]
  set-license-key

  [ANSWERS]
  ;Input new license key:;VcB542RSXtMZM\r;
  ;Repeat new license key:;VcB542RSXtMZM\r;

  EOM

Behind the scenes the provided answers in the [ANSWERS] section are translated automatically into an ad-hoc expect script, as:

  expect "Input new license key:"
  send -- "VcB542RSXtMZM\r"

  expect "Repeat new license key:"
  send -- "VcB542RSXtMZM\r"

  expect eof

that is used to remote control the command.

This helps to efficiently handle the most cases of remote command control where the needed expect definition would be a expect ... -> send -- ... sequence.

The [ANSWERS] section has the format:

:Input prompt:Answer:

where the first character is treated as separator between the Input prompt and the Answer fields.

Therefore, if the Input prompt or the Answer contains the field separator character (the colon : in this example) the specification

;Input prompt;Answer;

is identical to the specification above.

[EXPECT] Providing an expect script to a tty command:

Remote control an interactive command that reads the input from a tty and not from stdin.

The expect script has to be provided only if the automatically generated script using the [ANSWERS] section is not sufficient to the needs to control a command.

  ssh-exec -u user@target <<EOM

  [COMMANDS]
  set-license-key

  [EXPECT]
  expect "Input new license key:"
  send -- "VcB542RSXtMZM\r"

  expect "Repeat new license key:"
  send -- "VcB542RSXtMZM\r"

  expect eof

  EOM

OPTIONS

-h

usage message.

-p

only probe connection to target hostname with user without reading commands from stdin.
 

-e

use EDRC_USER as defined in etc/ssh-exec.cfg (default=edrc) as local user.

When -e is used or the EDRC_USER (default=edrc) is used in the -l localuser option, the private keys as defined in var/connection/security/edrc/OpenSSH/default/default/id_dsa and var/connection/security/edrc/OpenSSH/default/default/id_rsa are used to connect to the remote hostname.

Prerequisite to a working connection is that the contents of the files var/connection/security/edrc/OpenSSH/default/default/id_dsa.pub and var/connection/security/edrc/OpenSSH/default/default/id_rsa.pub are appended to the ~user/.ssh/authorized_keys file on the target hostname.

To efficiently add the public keys to authorized_keys files on hosts where the WA2L/edrc package is installed, use the ssh-keyadd(1m) command.

-s

output (to stderr) of commands and exit without executing any commands on hostname.

-v

verbose output (to stderr) of commands to be sent to target hostname.

-n

do not probe connection before executing the provided commands.

-b

eliminate the output of a banner of a remote system (when not providing a [ANSWERS] section).

-l localuser

use the local user localuser to initiate the connection. Default local user is root.

When using this option the private SSH keys of the specified localuser (as defined in ~localuser/.ssh/id_dsa and ~localuser/.ssh/id_rsa files) on the local system are used to connect to the target hostname.

See -e option description for additional information.

-u user

remote user to connect on the target system.

-t hostname

target system hostname to execute the commands.

-u user@hostname

remote user to connect on the target system hostname.

commands

commands to be executed on the target hostname.

Commands can be read from file using the input redirection:

  ssh-exec options < commands

providing the file contents thru the pipe:

  cat commands | ssh-exec options

or the 'in here' mechanism in scripts without the creation of an extra file:

  ssh-exec options <<EOM
  command_1
  command_2
  command_n
  EOM

ENVIRONMENT

EXIT STATUS

0

no error.

1

remote system is not up.

2

cannot conntect to hostname with user user.

4

usage printed.

5

the execution has been aborted using Ctrl+C.

6

the configuration file ssh-exec.cfg does not exist.

7

errors in [ANSWERS] section. If you receive this error, use the -v to see more details.

8

command was started with the -s option.

11

temporary directory could not be claimed or created in /tmp. Check the system temporary directory /tmp if you get this error, it is an indicator of system intrusion.

FILES

etc/ssh-exec.cfg

configuration file of ssh-exec, see ssh-exec.cfg(4) for more information.

var/log/ssh-exec.log

default logfile of ssh-exec.

EXAMPLES

SEE ALSO

NOTES

To poll a list of systems for reporting data most efficiently, use the syspoll(1) command.

BUGS

AUTHOR

COPYRIGHT

This is free software; see edrc/doc/COPYING for copying conditions. There is ABSOLUTELY NO WARRANTY; not even for MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.