.. contents::
NAME
----
**tsshbatch** - Run Commands On Batches Of Machines
.. WARNING:: ``tsshbatch`` is a powerful tool for automating activities
on many servers at a time. This also gives you to power
*to make many mistakes at a time!* This is especially
true if you have ``sudo`` privilege promotion
capabilities on the systems in your care. *So be careful
out there!*
We therefore STRONGLY recommend you do the following
things to mitigate this risk:
- Read This Fine Manual from beginning to end.
- Practice using ``tsshbatch`` on test machines or
VMs that can easily be recovered or reimaged if you
break someting.
- Make heavy use of test mode (which is the default)
to see what the program *would* do if it actually
ran in execution mode.
SYNOPSIS
--------
::
tsshbatch.py [-EKNSTaehkqstvxy -G 'file dest' -P 'file dest' -f cmdfile -l logfile -n name -p pw ] -H 'host ..' | hostlistfile [command arg ... ]
DESCRIPTION
-----------
``tsshbatch`` is a tool to enable you to issue a command to many
hosts without having to log into each one separately. When writing
scripts, this overcomes the ``ssh`` limitation of not being able to
specify the password on the command line.
You can also use ``tsshbatch`` to ``GET`` and ``PUT`` files
from- and to many hosts at once.
``tsshbatch`` also understands basic ``sudo`` syntax and can be used
to access a host, ``sudo`` a command, and then exit.
``tsshbatch`` thus allows you to write complex, hands-off scripts that
issue commands to many hosts without the tedium of manual login and
``sudo`` promotion. System administrators, especially, will find this
helpful when working in large server farms.
OPTIONS
-------
``tsshbatch`` supports a variety of options which can be specified
on either the command line or in the ``$TSSHBATCH`` environment
variable:
-E Normally, ``tsshbatch`` writes it's own errors
to ``stderr``. It also writes the ``stderr``
output from each host it contacts to the local
shell's ``stderr`` (unless the ``-e`` option has
been selected).
The ``-E`` option redirects any such ``tsshbatch``
output intended for ``stderr`` to ``stdout``
instead. This avoids the need to do things like
``2>&1 | ...` on the command line when you want to
pipe all ``tsshbatch`` output to another program.
-K Force prompting for passwords. This is used
to override a prior ``-k`` argument.
-G spec GET file on host and write local dest directory.
``spec`` is a quoted pair of strings. The first
specifies the path of the source file (on the
remote machine) to copy. The second, specifies
the destination *directory* (on the local
machine)::
tsshbatch.py -G "/foo/bar/baz /tmp" hostlist
This copies ``/foo/bar/baz`` from every machine in
``hostlistfile`` to the local ``/tmp/`` directory.
Since all the files have the same name, they would
overwrite each other if copied into the same
directory. So, ``tsshbatch`` prepends the string
``hostname-`` to the name of each file it saves
locally.
-H hostlistfile List of hosts on which to run the command. This should
be enclosed in *quotes* so that the list of hosts
is handed to the -H option as a single argument::
-H 'host1 host2 host3'
-N Force interactive username dialog. This cancels
any previous request for key exchange authentication.
-P spec PUT file from local machine to remote machine destination
directory. ``spec`` is a quoted pair of strings.
The first specifies the path of the source file (on
the local machine) to copy. The second, specifies
the destination *directory* (on the remote machine)::
tsshbatch.py -P "/foo/bar/baz /tmp" hostlist
This copies ``/foo/bar/baz`` on the local
machine to ``/tmp/`` on every host in ``hostlist``.
-S Force prompting for sudo password
-T seconds Timeout for ssh connection attempts (Default: 15 seconds)
-a Don't abort program after failed file transfers.
Continue to next transfer attempt. (Default: Abort)
-e Don't report remote host ``stderr`` output
-f cmdfile Read commands from a file. This file can be commented
freely with the ``#`` character. Leading- and
trailing whitespace on a line are ignored.
-h Print help information
-k Use ssh keys instead of name/password credentials
-l logfile Log diagnostic output to ``logfile`` (Default: /dev/null)
-n name Login name to use
-p pw Password to use when logging in and/or doing sudo
-q Quiet mode - produce less noisy output. Turns off ``-y``.
-s Silence all program noise - only return command output.
Applies only to command operations. File transfer
and error reporting, generally, are unaffected.
-t Test mode: Only show what *would* be done but don't
actually do it. This also prints diagnostic
information about any variable definitions, the list
of hosts, any ``GET`` and ``PUT`` requests, and final
command strings after all variable substitutions have
been applied. This is the default program behavior.
-v Print detailed program version information and exit
-x Override any previous ``-t`` specifications and
actually execute the commands. This is useful
if you want to put ``-t`` in the ``$TSSHBATCH``
environment variable so that the default is
always run the program in test mode. Then, when
you're ready to actually run commands, you can
override it with ``-x`` on the command line.
-y Turn on 'noisy' reporting for additional detail on
every line, instead of just at the top of the
``stdout`` and ``stderr`` reporting. This is
helpful when you are filtering the output through
something like ``grep`` that only returns matching
lines and thus no context information. Turns off ``-q``.
If the ``-H`` option is not selected, the item immediately following
the options is understood to be the name of the ``hostlistfile``.
This is a file that contains the name of each host - one per line - on
which to run the commands. This file can be commented freely with the
``#`` character. Leading- and trailing whitespace on a line are
ignored.
The last entry on the command line is optional and defines a command
to run. ``tsshbatch`` will attempt to execute it on every host you've
specified either via ``-H`` or a ``hostlistfile``::
tsshbatch.py -Hmyhost ls -al /etc
This will do a ``ls -al /etc`` on ``myhost``.
Be careful when using metacharacters like ``&&, <<, >>, <, >`` and so
on in your commands. You have to escape and quote them properly or
your local shell will interfere with them being properly conveyed to
the remote machine.
If you've specified a ``cmdfile`` containing the commands you want run via
the ``-f`` option, these commands will run *before* the command
you've defined on the command line. It is always the last command
run on each host.
You can put as many ``-f`` arguments as you wish on the command
line and the contents of these files will be run in the order
they appeared from left-to-right on the command line.
``tsshbatch`` does all the ``GETs``, then all the ``PUTs`` before
attempting to do any command processing. If no ``GETs``, ``PUTs``, or
commands have been specified, ``tsshbatch`` will exit silently, since
"nothing to do" really isn't an error.
ENVIRONMENT
-----------
``tsshbatch`` respects the ``$TSSHBATCH`` environment variable. You
may set this variable with any options above you commonly use to avoid
having to key them in each time you run the program. For example::
export TSSHBATCH="-n jluser -p l00n3y"
This would cause all subsequent invocations of ``tsshbatch`` to
attempt to use the login name/password credentials of ``jluser`` and
``l00n3y`` respectively.
``tsshbatch`` also supports searching for files over specified
paths with the ``$TSSHBATCHCMDS`` and ``$TSSHBATCHHOSTS`` environment
variables. Their use is described later in this document.
FEATURES AND USE CASES
----------------------
The sections below describe the various features of ``tsshbatch`` in
more detail as well as common use scenarios.
Different Ways To Specify Targeted Hostnames
============================================
There are two ways to specify the list of hosts on which you want
to run the specified command:
- On the command line via the ``-H`` option::
tsshbatch.py -H 'hostA hostB' uname -a
This would run the command ``uname -a`` on the
hosts ``hostA`` and ``hostB`` respectively.
Notice that the list of hosts must be separated by spaces but
passed as a *single argument*. Hence we enclose them in single
quotes.
- Via a host list file::
tsshbatch.py myhosts df -Ph
Here, ``tsshbatch`` expects the file ``myhosts`` to contain a list
of hosts, one per line, on which to run the command ``df -Ph``. As
an example, if you want to target the hosts ``larry``, ``curly``
and ``moe`` in ``foo.com``, ``myhosts`` would look like this::
larry.foo.com
curly.foo.com
moe.foo.com
This method is handy when there are standard "sets" of hosts on
which you regularly work. For instance, you may wish to keep a
host file list for each of your production hosts, each of your
test hosts, each of your AIX hosts, and so on.
You may use the ``#`` comment character freely throughout a host
list file to add comments or temporarily comment out a particular
host line.
You can even use the comment character to temporarily comment out
one or most hosts in the list given to the ``-H`` command line
argument. For example::
tsshbatch.py -H "foo #bar baz" ls
This would run the ``ls`` command on hosts ``foo`` and ``baz`` but
not ``bar``. This is handy if you want to use your shell's
command line recall to save typing but only want to repeat the
command for some of the hosts your originally Specified.
Authentication Using Name And Password
======================================
The simplest way to use ``tsshbatch`` is to just name the hosts
can command you want to run::
tsshbatch.py linux-prod-hosts uptime
By default, ``tsshbatch`` uses your login name found in the ``$USER``
environment variable when logging into other systems. In this
example, you'll be prompted only for your password which ``tsshbatch``
will then use to log into each of the machines named in
``linux-prod-hosts``. (*Notice that his assumes your name and
password are the same on each host!*)
Typing in your login credentials all the time can get tedious after
awhile so ``tsshbatch`` provides a means of providing them on the
command line::
tsshbatch.py -n joe.luser -p my_weak_pw linux-prod-hosts uptime
This allows you to use ``tsshbatch`` inside scripts for hands-free
operation.
If your login name is the same on all hosts, you can simplify this
further by defining it in the environment variable::
export TSSHBATCH="-n joe.luser"
Any subsequent invocation of ``tsshbatch`` will only require a
password to run.
HOWEVER, there is a huge downside to this - your plain text password
is exposed in your scripts, on the command line, and possibly your
command history. This is a pretty big security hole, especially if
you're an administrator with extensive privileges. (This is why the
``ssh`` program does not support such an option.) For this reason, it
is strongly recommended that you use the ``-p`` option sparingly, or
not at all. A better way is to push ssh keys to every machine and use
key exchange authentication as described below.
However, there are times when you do have use an explicit password,
such as when doing ``sudo`` invocations. It would be really nice to
use ``-p`` and avoid having to constantly type in the password. There
are two strategies for doing this more securely than just entering it
in plain text on the command line:
- Temporarily store it in the environment variable::
export TSSHBATCH="-n joe.luser -p my_weak_pw"
Do this *interactively* after you log in, not from a script
(otherwise you'd just be storing the plain text password in a
different script). The environment variable will persist as long
as you're logged in and disappear when you log out.
If you use this just make sure to observe three security
precautions:
1) Clear your screen immediately after doing this so no one
walking by can see the password you just entered.
2) Configure your shell history system to ignore commands
beginning with ``export TSSHBATCH``. That way your plain
text password will never appear in the shell command history.
3) Make sure you don't leave a logged in session unlocked so
that other users could walk up and see your password by
displaying the environment.
This approach is best when you want your login credentials
available for the duration of an *entire login session*.
- Store your password in an encrypted file and decrypt it inline.
First, you have to store your password in an encrypted format.
There are several ways to do this, but ``gpg`` is commonly used::
echo "my_weak_pw" | gpg -c >mysecretpw
Provide a decrypt passphrase, and you're done.
Now, you can use this by decrypting it inline as needed::
#!/bin/sh
# A demo scripted use of tsshbatch with CLI password passing
MYPW=`cat mysecretpw | gpg` # User will be prompted for unlock passphrase
tsshbatch.py -n joe.luser -p $MYPW hostlist1 command1 arg
tsshbatch.py -n joe.luser -p $MYPW hostlist2 command2 arg
tsshbatch.py -n joe.luser -p $MYPW hostlist3 command3 arg
This approach is best when you want your login credentials
available for the duration of *the execution of a script*. It
does require the user to type in a passphrase to unlock the
encrypted password file, but your plain text password never
appears in the wild.
Authentication Using Key Exchange
=================================
For most applications of ``tsshbatch``, it is much simpler to use
key-based authentication. For this to work, you must first have
pushed ssh keys to all your hosts. You then instruct ``tsshbatch`` to
use key-based authentication rather than name and password. Not only
does this eliminate the need to constantly provide name and password,
it also eliminates passing a plain text password on the command line
and is thus far more secure. This also overcomes the problem of
having different name/password credentials on different hosts.
By default, ``tsshbatch`` will prompt for name and password if they
are not provided on the command line. To force key- authentication,
use the ``-k`` option::
tsshbatch.py -k AIX-prod-hosts ls -al
This is so common that you may want to set it in your ``$TSSHBATCH``
environment variable so that keys are used by default. If you do
this, there may still be times when you want for force prompting for
passwords rather than using keys. You can do this with the ``-K``
option which effectively overrides any prior ``-k`` selection.
Executing A ``sudo`` Command
============================
``tsshbatch`` is smart enough to handle commands that begin with the
``sudo`` command. It knows that such commands *require* a password no
matter how you initially authenticate to get into the system. If you
provide a password - either via interactive entry or the ``-p``
option - by default, ``tsshbatch`` will use that same password for
``sudo`` promotion.
If you provide no password - you're using ``-k`` and have not provided
a password via ``-p`` - ``tsshbatch`` will prompt you for the password
``sudo`` should use.
You can force ``tsshbatch`` to ask you for a ``sudo`` password with
the ``-S`` option. This allows you to have one password for initial
login, and a different one for ``sudo`` promotion.
Any time you a prompted for a ``sudo`` password and a login password
has been provided (interactive or ``-p``), you can accept this as the
``sudo`` password by just hitting ``Enter``.
.. NOTE:: ``tsshbatch`` makes a reasonable effort to scan your command
line and/or command file contents to spot explicit
invocations of the form ``sudo ...``. It will ignore these
if they are inside single- or double quoted strings, on the
assumption that you're quoting the literal string ``sudo
...`` for some other purpose.
However, this is not perfect because it is not a full
reimplementation of the shell quoting and aliasing features.
For example, if you invoke an alias on the remote machine
that resolves to a ``sudo`` command, or you run a script
with a ``sudo`` command in it, ``tsshbatch`` has no way to
determine what you're trying to do. For complex
applications, it's best to write a true shell script, push
it all the machines in question via ``-P``, and then have
``tsshbatch`` remotely invoke it with ``sudo myscript`` or
something similar.
As always, the best way to figure out what the program
thinks you're asking for is to run it in test mode and look
at the diagnostic output.
Precedence Of Authentication Options
====================================
``tsshbatch`` supports these various authentication options in a
particular heirarchy using a "first match wins" scheme. From highest
to lowest, the precedence is:
1. Key exchange
2. Forced prompting for name via -N. Notice this cancels any
previously requested key exchange authentication.
3. Command Line/$TSSHBATCH environment variable sets name
4. Name picked up from $USER (Default behavior)
If you try to use Key Exchange and ``tsshbatch`` detects a command
beginning with ``sudo``, it will prompt you for a password anyway.
This is because ``sudo`` requires a password to promote privilege.
File Transfers
==============
The ``-G`` and ``-P`` options specify file ``GET`` and ``PUT``
respectively. Both are followed by a quoted file transfer
specification in the form::
"path-to-source-file path-to-destination-directory"
Note that this means the file will always be stored under its original
name in the destination directory. *Renaming isn't possible during
file transfer*.
However, ``tsshbatch`` always does ``GETs`` then ``PUTs`` *then* any
outstanding command (if any) at the end of the command line. This
permits things like renaming on the remote machine after a ``PUT``::
tsshbatch.py -P "foo ./" hostlist mv -v foo foo.has.a.new.name
``GETs`` are a bit of a different story because you are retrieving a
file of the same name on every host. To avoid having all but the last
one clobber the previous one, ``tsshbatch`` makes forces the files you
``GET`` to be uniquely named by prepending the hostname and a "-" to
the actual file name::
tsshbatch.py -H myhost -G "foo ./"
This saves the file ``myhost-foo`` in the ``./`` on your a local
machine.
These commands do not recognize any special directory shortcut symbols
like ``~/`` like the shell interpreter might. You must name file and
directory locations using ordinary pathing conventions. You can put
as many of these requests on the command line as you like to enable
``GETs`` and ``PUTs`` of multiple files. You cannot, however, use
filename wildcards to specify multi-file operations.
You can put multiple ``GETs`` or ``PUTs`` on the command line for the
same file. They do not override each other but are *cummulative*. So
this::
tsshbatch.py -P"foo ./" -P"foo /tmp" ...
Would put local file ``foo`` in both ``./`` and ``/tmp`` on each host
specified. Similarly, you can specify multiple files to ``GET`` from
remote hosts and place them in the same local directory::
tsshbatch.py -G"/etc/fstab ./tmp" -G"/etc/rc.conf ./tmp" ...
You may also put file transfer specifications into a ``cmdfile`` via
the ``.getfile`` and ``.putfile`` directives. This is handy when you
have many to do and don't want to clutter up the command line. Each
must be on its own line in the ``cmdfile`` and in the same form as if
it were provided on the command line::
.getfile /path/to/srcfile destdir # This will get a file
.putfile /path/to/srcfile destdir # This will put a file
File transfers are done in the order they appear. For instance, if
you have a file transfer specification on the command line and then
make reference to a ``cmdfile`` with a file transfer specification in
it, the one on the command line gets done first.
.. NOTE:: Keep in mind that ``tsshbatch`` always processes file
transfers *before* executing any commands, no matter what
order they appear in the ``cmdfile``. If you have this in a
``cmdfile``::
echo "Test"
.putfile "./myfile /foo/bar/baz/"
The file will be transferred *before* the ``echo`` command
gets run. This can be counterintuitive. It's therefore
recommended that you put your file transfers into a single
file, and ``.include`` it as the first thing in your
``cmdfile`` to make it obvious that these will be run first.
By default, ``tsshbatch`` aborts if any file transfer fails. This is
unlike the case of failed commands which are reported but do *not*
abort the program. The rationale' for this is that you may be doing
both file transfer and command execution with a single ``tsshbatch``
invocation, and the commands may depend on a file being transfered
first.
If you are sure no such problem exists, you can use the ``-a`` option
to disable abort-after-failure semantics on file transfer. In this
case, file transfer errors will be reported, but ``tsshbatch`` will
continue on to the next transfer request.
``tsshbatch`` does preserve permissions when transferring files.
Obviously, for this to work, the destination has to be writable by the
ID you're logging in with.
.. NOTE:: The file transfer logic cannot cope with filenames that
contain spaces. The workaround is to either temporarily
rename them, or put them in a container like a tarball or
zip file and transfer that instead.
Commenting
==========
Both the ``cmdfile`` and ``hostlistfile`` can be freely commented
using the ``#`` character. Everything from that character to the end
of that line is ignored. Similarly, you can use whitespace freely,
except in cases where it would change the syntax of a command or host
name.
Includes
========
You may also include other files as you wish with the ``.include
filename`` directive anywhere in the ``cmdfile`` or ``hostlistfile``.
This is useful for breaking up long lists of things into smaller
parts. For example, suppose you have three host lists, one for each
major production areas of your network::
hosts-development
hosts-stage
host-production
You might typically run different ``tsshbatch`` jobs on each of these
sets of hosts. But suppose you now want to run a job on all of them.
Instead of copying them all into a master file (which would be
instantly obsolete if you changed anything in one of the above files),
you could create ``hosts-all`` with this content::
.include hosts-development
.include hosts-stage
.include hosts-production
that way if you edited any of the underlying files, the
``hosts-all`` would reflect the change.
Similarly you can do the same thing with the ``cmdfile`` to group
similar commands into separate files and include them.
``tsshbatch`` does not enforce a limit on how deeply nested
``.includes`` can be. An included file can include another file and
so on. However, if a circular include is detected, the program will
notify you and abort. This happens if, say, file1 includes file2,
file2 includes file3, and file3 includes file1. This would create an
infinite loop of includes if permitted. You can, of course, include
the same file multiple times, either in a single file or throughout
other included files, so long as no circular include is created.
Search Paths
============
``tsshbatch`` supports the ablity to search paths to find files you've
referenced. The search path for ``cmdfiles`` is specified in the
``$TSSHBATCHCMDS`` environment variable. The ``hostlistfiles`` search
path is specified in the ``$TSSHBATCHHOSTS`` environment variable.
These are both in standard path delimited format for your operating
system. For example, on Unix-like systems these look like this::
export TSSHBATCHCMDS="/usr/local/etc/.tsshbatch/commands:/home/me/.tsshbatch/commands"
And so forth.
These paths are honored both for any files you specify on the command
line as well as for any files you reference in a ``.include``
directive. This allows you to maintain libraries of standard commands
and host lists in well known locations and ``.include`` the ones you
need.
``tsshbatch`` will always first check to see if a file you've
specified is in your local (invoking) directory and/or whether it is a
fully qualified file name before attempting to look down a search
path. If a file exist in several locations, the first instance found
"wins". So, for instance, if you have a file called ``myhosts``
somewhere in the path defined in ``$TSSHBATCHHOSTS``, you can override
it by creating a file of same name in your current working directory.
``tsshbatch`` also checks for so-called "circular includes" which
would cause an infinite inclusion loop. It will abort upon
discovering this, prior to any file transfers or commands being
executed.
An Overview Of Variables
========================
As you become more sophisticated in your use of ``tsshbatch``, you'll
begin to see the same patterns of use over and over again. Variables
are a way for you to use "shortcuts" to reference long strings
without having to type the whole string in every time. So, for example,
instead of having to type in a command like this::
myfinecommand -X -Y -x because this is a really long string
You can just define variable like this::
.define __MYCMD__ = myfinecommand -X -Y -x because this is a really long string
From then on, instead of typing in that long command on the command line or in
a command file, you can just use ``__MYCMD__`` and ``tsshbatch`` will substitute
the string as you defined it whenever it encounters the variable.
Variables can be used pretty much everwhere:
- In ``hostlistfiles`` or in the hostnames listed with ``-H``::
.define __MYDOMAIN__ = stage.mydomain.com
#.define __MYDOMAIN__ = prod.mydomain.com
host1.__MYDOMAIN__
host2.__MYDOMAIN__
Now you can switch ``tsshbatch`` operation from stage to prod simply
by changing what is commented out at the beginning.
- In file transfer specifications::
tsshbatch.py -xP"./fstab-__MYHOSTNAME__ ./" hostlist
tsshbatch.py -xG"/etc/__OSNAME__-release ./" hostlist
- In ``cmdfiles``::
.define __SHELL__ = /usr/local/bin/bash
__SHELL__ -c myfinescript
.. NOTE:: A variable can have pretty much any name you like excepting
the use of metacharacters like ``<`` or ``!``. But if
you are not careful, you can cause unintended errors::
.define foo = Slop
myfoodserver.foods.com
When you run ``tsshbatch`` it will then turn the server name
into ``mySlopdserver.Slopds.com`` - probably not what you
want.
So, it's a Really Good Idea (tm) to use some kind of naming
scheme to make variables names stand out and make them
unlikely to conflict accidentally with command- and host
strings.
Types Of Variables
==================
``tsshbatch`` has three different kinds of variables:
- *User Defined Variables* are the kind in the example above.
You, the user, define them as you wish in a ``cmdfile`` or
``hostlistfile``.
- *Execution Variables* run any program or script of your choosing
(on the same machine you're running ``tsshbatch``) and assign
the results to a variable.
- *Builtin Variables* are variables the ``tsshbatch`` itself
defines. You can override their default values by creating
a User Defined Variable of the same name.
Where And When Do Variables Get Processed?
==========================================
User Defined and Execution Variables are defined in either a
``hostlistfile`` or ``cmdfile``.
Builtin Variables are defined within ``tsshbatch`` itself unless you
override them.
User Defined Variables are *all* read in and *then* used. If you do
something like this::
.define __FOO__ = firstfoo
echo __FOO__
.define __FOO__ = secondfoo
You'll get an output of ... ``secondfoo``! Why? Because before
``tsshbatch`` tries to run anything, it has to process all the
``cmdfiles``, ``hostlistfile``, and the command line content. So,
before we ever get around to doing an ``echo __FOO__`` on some host,
the second definition of __FOO__ has been read in ... and last
definition wins.
Execution Variables are like User Defined Variables. They get
processed a single time *at the time they're read in* from a
``cmdfile`` or ``hostlistfile``.
Builtin Variables get evaluated *every time ``tsshbatch`` prepares to
connect to a new host* (unless you've overriden them). That way, the
most current value for them is available for use on the next host.
Keep in mind that ``tsshbatch`` isn't a programming language. It's
"variables" are simple string substitutions with "last one wins"
semantics. There is no notion of scope, for example. If you define
the same variable in, say, a ``cmdfile`` and also in the
``hostlistfile``, the latter will "win". Why? Because
``hostlistfiles`` are always read in after any ``cmdfiles``.
Finally, variable references in a definition are *ignored*. Say you
do this in a ``cmdfile``::
.define __CLEVER __ = __REALLYCLEVER__
.define __REALLYCLEVER__ = Not That Smart
echo __CLEVER__
You will get this output, ``__REALLYCLEVER__``! Why? Because, the
variable references on the right side of a definition statement are
never replaced. This is a concious design choice to keep variable
definition and use as simple and obvious as possible. Allowing such
"indirect" definitions opens up a treasure trove of maintenance pain
you really want to avoid. Trust us on this one.
User-Defined Variables
======================
``tsshbatch`` allows you to define variables which will then be used
to replace matching strings in ``cmdfiles``, ``hostlistfiles``, and
file transfer specifications. For example, suppose you have this in a
``hostlistfile``::
.define DOMAIN=.my.own.domain.com
host1DOMAIN
host2DOMAIN
host3DOMAIN
At runtime, the program will actually connect to
``host1.my.own.domain.com``, ``host2.my.domain.com``, and so on. This
allows for ease of modularization and maintenance of your files.
Similarly, you might want define ``MYCMD=some_long_string`` so you
don't have to type ``some_long_string`` over and over again in a
``cmdfile``.
There are some "gotchas" to this:
- The general form of a variable definition is::
.define name = value
You have to have a name but the value is optional. ``.define
FOO=`` simply replaces any subsequent ``FOO`` strings with
nothing, effectively removing them.
Any ``=`` symbols to the right of the one right after ``name`` are
just considered part of the variable's value.
Whitespace around the ``=`` symbol is optional but allowed.
- Variables are substituted in the order they appear::
.define LS = ls -alr
LS /etc # ls -alr /etc
.define LS = ls -1
LS /foo # ls -1 /foo
- Variable names and values are *case sensitive*.
- Variables may be defined in either ``cmdfiles`` or
``hostlistfiles`` but they are *visible to any subsequent file
that gets read*. For instance, ``cmdfiles`` are read before any
``hostlistfiles``. Any variables you've defined in a ``cmdfile``
that happen to match a string in one of your hostnames will be
substituted.
This is usually not what you want, so be careful. One way to
manage this is to use variables names that are highly unlikely to
ever show up in a hostname or command. That way your commands and
hostnames will not accidentally get substrings replaced with
variable values. For example, you might use variable names like
``--MYLSCOMMAND--`` or ``__DISPLAY_VGS__``.
- Variable substitution is also performed on any host names
or commands passed on the command line.
Execution Variables
===================
Execution Variables are actually a special case of User Defined
Variables. That is, they are evaluated at the same time and in the
same manner as any other User Defined Variable. The difference is
that a User Defined Variable describes a *literal string replacement*.
But an Execution Variable *runs a command, program, or script and
assigns the results to the variable*.
For example, suppose you want create a file on many machines, and you
want that file to be named based on who ran the ``tsshbatch`` job.
You might do this in a ``cmdfile``::
.define __WHOAMI__ = ! whoami
touch __WHOAMI__-Put_This_Here.txt
So, if ID ``luser`` is running ``tsshbatch``, a file called
``luser-Put_This_Here.txt`` will be created (or have its timestamp
updated) on every machine in the ``hostlistfile`` or named with
``-H``.
Notice it is the ``!`` character that distinguishes an Execution
Variable from a User Defined Variable. It is this character that
tells ``tsshbatch``, "Go run the command to the right of me and return
the results." The trailing space is optional and the definition could
be written as::
.define __WHOAMI__ = !whoami
If the command you specify returns multiple lines of output, it's up
to you to process it properly. ``tsshbatch`` does no newline
stripping or other postprocessing of the command results. This can
make the output really "noisy". ``tssbatch`` normally reports
a summary of the command and its results. But if you do something
like this::
.define __LS__ = ! ls -al
echo __LS__
You will get a multiline summary of the command and then the actual
output - which is also multiline. This gets to be obnonxious pretty
quickly. You can make a lot of this go away with the ``-q``, or
"quiet" option.
.. NOTE:: It's important to remember that the program you are invoking
*runs on the same machine as* ``tsshbatch`` *itself*, NOT each
host you are sending commands to. In other words, just
like Builtin Variables, Execution Variables are *locally
defined*.
Builtin Variables
=================
As noted previously, Builtin Variables are created by ``tsshbatch``
itself. They are created for each new host connection so that things
like time, host number, and hostname are up-to-date.
As of this release, ``tsshbatch`` supports the following Builtins:
==================== ===============================================
``__DATE__`` Date in YYYYMMDD format
``__DATETIME__`` Date and time in YYYYMMDDHHMMSS format
``__HOSTNAME__`` Full name of current host as passed to ``tsshbatch``
``__HOSTNUM__`` Count of host being processed, starting at 1
``__HOSTSHORT__`` Leftmost component of hostname as passed to ``tsshbatch``
``__LOGINNAME__`` User name used for remote login. For key auth, name of tsshbatch user.
``__TIME__`` Time in HHMMSS format
==================== ===============================================
Using Builtin Variables
=======================
There are times when it's convenient to be able to embed the name of
the current host in either a command or in a file transfer
specification. For example, suppose you want to use a single
invocation of ``tsshbatch`` to transfer files in a host-specific way.
You might name your files like this::
myfile.host1
myfile.host2
Now, all you have to do is this::
tsshbatch.py -xH "host 1 host2" -P "myfile.__HOSTNAME__ ./"
When run, ``tsshbatch`` will substitute the name of the current host
in place of the string ``__HOSTNAME__``. (*Note that these are
**double** underbars on each side of the string.*)
You can do this in commands (and commands within command files) as
well::
tsshbatch.py -x hosts 'echo I am running on __HOSTNAME__'
Be careful to escape and quote things properly, especially from the
the command line, since ``<`` and ``>`` are recognized by the shell as
metacharacters.
There are two forms of host name substitution possible. The first,
``__HOSTNAME__`` will use the name *as you provided it*, either as an
argument to ``-H`` or from within a host file.
The second, ``__HOSTSHORT__``, will only use the portion of the name
string you provided up to the leftmost period.
So, if you specify ``myhost1.frumious.edu``, ``__HOSTNAME__`` will be
replaced with that entire string, and ``__HOSTSHORT__`` will be
replaced by just ``myhost1``.
Notice that, in no case does ``tsshbatch`` do any DNS lookups to
figure this stuff out. It just manipulates the strings you provide as
hostnames.
The symbols ``__HOSTNAME__`` and ``__HOSTSHORT__`` are like any other
symbol you might have specified yourself with ``.define``. *This
means you can override their meaning*. For instance, say you're doing
this::
tsshbatch.py -x myhosts echo "It is: __HOSTNAME__"
As you would expect, the program will log into that host, echo the
hostname and exit. But suppose you don't want it to echo something
else for whatever reason. You'd create a command file with this
entry::
.define __HOSTNAME__ = Really A Different Name
Now, when you run the command above, the output is::
It is: Really A Different Name
In other words, ``.define`` has a *higher precedence* than the
preconfigured values of ``HOSTNAME`` and ``HOSTSHORT``.
Noise Levels
============
``tsshbatch`` defaults to a medium level of reporting as it runs.
This includes connection reporting, headers describing the command
being run on every host,and the results written to ``stdin`` and
``stdout``. Each line of reporting output begins with ``--->`` to
help you parse through the output if you happen to be writing a
program that post-processes the results from ``tsshbatch``.
This output "noise" is judged to be right for most applications of the
program. There are times, however, when you want more- or less
"noise" in the output. There are several ``tsshbatch`` options that
support this.
These options *only affect reporting of
commands you're running*. They do not change the output of file
transfer operations. They also do not change error reporting, which
is always the same irrespective of current noise level setting.
``-q`` or "quiet" mode, reduces the amount of output noise in
two ways. First, it silences reporting each time a successful
connection is made to a host. Secondly, the command being run
isn't reported in the header. For example, normally, running
``ls -l`` is reported like this::
---> myhost: SUCCESS: Connection Established
---> myhost (stdout) [ls -l]:
...
---> myhost (stderr) [ls -l]:
In quiet mode, reporting looks like this::
---> localhost (stdout):
...
---> localhost (stderr):
The main reason for this is that some commands can be very long.
With execution variables, it's possible to create commands that
span many lines. The quiet option gives you the ability to
suppress echoing these long commands for each and every host
in your list.
``-y`` or "noisy" mode, produces normal output noise but
also replicates the hostname and command string *for
every line of output produced*. For instance, ``ls -1``
might normally produce this::
---> myhost: SUCCESS: Connection Established
---> myhost (stdout) [ls -1]:
backups
bin
But in noisy mode, you see this::
---> myhost: SUCCESS: Connection Established ---> myhost (stdout) [ls -1]:
[myhost (stdout) [ls -1]] backups
[myhost (stdout) [ls -1]] bin
Again, the purpose here is to support post-processing where you might
want to search through a large amount of output looking only for
results from particular hosts or commands.
``-s`` or "silent" mode returns *only the results from running the
commands*. No headers or descriptive information are produced. It's
more-or-less what you'd see if you logged into the host and ran the
command interactively. For instance, ``ls -l`` might look like this::
total 44
drwxr-xr-x 2 splot splot 4096 Nov 5 14:54 Desktop
drwxrwxr-x 39 splot splot 4096 Sep 9 14:57 Dev
drwxr-xr-x 3 splot splot 4096 Jun 14 2012 Documents
The idea here is to use silent mode with the various variables
described previously to customize your own reporting output. Imagine
you have this in a ``cmdfile`` and you run ``tsshbatch`` in silent
mode::
.define __USER__ = ! echo $USER
echo "Run on __HOSTNAME__ on __DATE__ at __TIME__ by __USER__"
uname -a
You'd see output along these lines::
Run on myhost on 20991208 at 141659 by splot
Linux myhost 3.11.0-12-generic #19-Ubuntu SMP Wed Oct 9 16:20:46 UTC 2013 x86_64 x86_64 x86_64 GNU/Linux
OTHER
-----
- Comments can go anywhere.
- Directives like ``.define`` and ``.include`` must be the first
non-whitespace text on the left end of a line. If you do this in a
``cmdfile``::
foo .include bar
``tsshbatch`` thinks you want to run the command ``foo`` with an
argument of ``.include bar``. If you do it in a ``hostlistfile``,
the program thinks you're trying to contact a host called ``foo
.include bar``. In neither case is this likely to be quite what you
had in mind. Similarly, everything to the right of the directive is
considered its argument (up to any comment character).
- Whitespace is not significant at the beginning or end of a line but
it is preserved within ``.define`` and ``.include`` directive
arguments as well as within commmand definitions.
- Strictly speaking, you do not have to have whitespace after a
directive. This is recognized::
.includesomefileofmine
.definemyvar=foo
But this is *strongly* discouraged because it's really hard to read.
- ``tsshbatch`` writes the ``stdout`` of the remote host(s) to
``stdout`` on the local machine. It similarly writes remote
``stderr`` output to the local machine's ``stderr``. If you wish to
suppress ``stderr`` output, either redirect it on your local command
line or use the ``-e`` option to turn it off entirely. If you want
everything to go to your local ``stdout``, use the ``-E`` option.
- You must have a reasonably current version of Python 2.x installed.
It almost certainly will not work on Python 3.x because it uses the
deprecated ``commands`` module. This decision was made to make the
program as backward compatible with older versions of Python as
possible (there is way more 2.x around than there is 3.x).
- If your Python installation does not install ``paramiko`` you'll
have to install it manually, since ``tsshbatch`` requires these
libraries as well.
- ``tsshbatch`` has been run extensively from Unix-like systems (Linux,
FreeBSD) and has had no testing whatsoever on Microsoft Windows. If
you have experience using it on Windows, do please share with the
class using the email address below. While we do not officially
support this tool on Windows, if the changes needed to make it work
properly are small enough, we'd consider updating the code
accordingly.
BUGS AND MISFEATURES
--------------------
- You will not be able to run remote ``sudo`` commands if the host in
question enables the ``Defaults requiretty`` in its ``sudoers``
configuration. Some overzealous InfoSec folks seem to think this is
a brilliant way to secure your system (they're wrong) and there's
nothing ``tsshbatch`` can do about it.
- When ``sudo`` is presented a bad password, it ordinarily prints a
string indicating something is wrong. ``tsshbatch`` looks for this
to let you know that you've got a problem and then terminates
further operation. This is so that you do not attempt to log in
with a bad password across all the hosts you have targeted. (Many
enterprises have policies to lock out a user ID after some small
number of failed login/access attempts.)
However, some older versions of ``sudo`` (noted on a RHEL 4 host
running ``sudo`` 1.6.7p5) do not return any feedback when presented
with a bad password. This means that ``tsshbatch`` cannot tell the
difference between a successful ``sudo`` and a system waiting for
you to reenter a proper password. In this situation, if you enter a
bad password, the *the program will hang*. Why? ``tsshbatch``
thinks nothing is wrong and waits for the ``sudo`` command to
complete. At the same time, ``sudo`` itself is waiting for an
updated password. In this case, you have to kill ``tsshbatch`` and
start over. This typically requires you to put the program in
background (```Ctrl-Z`` in most shells) and then killing that job
from the command line.
There is no known workaround for this problem.
OTHER, SIMILAR PRODUCTS
-----------------------
It's always interesting to see how other people approach the same
problem. If you're interested in this general area of IT automation,
you may want to also look at ``Ansible``, ``Capistrano``, ``Cluster
SSH``, ``Fabric``, ``Func``, and ``Rundeck``.
COPYRIGHT AND LICENSING
-----------------------
**tsshbatch** is Copyright (c) 2011-2014 TundraWare Inc.
For terms of use, see the ``tsshbatch-license.txt`` file in the
program distribution. If you install **tsshbatch** on a FreeBSD
system using the 'ports' mechanism, you will also find this file in
``/usr/local/share/doc/tsshbatch``.
AUTHOR
------
::
Tim Daneliuk
tsshbatch@tundraware.com
DOCUMENT REVISION INFORMATION
-----------------------------
::
$Id: tsshbatch.rst,v 1.164 2014/12/10 15:41:56 tundra Exp $
This document was produced with ``emacs``, ``RestructuredText``, and ``TeX Live``.
You can find the latest version of this program at:
http://www.tundraware.com/Software/tsshbatch
tundra