I already have an ssh agent set up, and I can run commands on an external server in Bash script doing stuff like:
ssh blah_server "ls; pwd;"
Now, what I'd really like to do is run a lot of long commands on an external server. Enclosing all of these in between quotation marks would be quite ugly, and I'd really rather avoid ssh'ing multiple times just to avoid this.
So, is there a way I can do this in one go enclosed in parentheses or something? I'm looking for something along the lines of:
ssh blah_server (
ls some_folder;
./someaction.sh;
pwd;
)
Basically, I'll be happy with any solution as long as it's clean.
Edit
To clarify, I'm talking about this being part of a larger bash script. Other people might need to deal with the script down the line, so I'd like to keep it clean. I don't want to have a bash script with one line that looks like:
ssh blah_server "ls some_folder; ./someaction.sh 'some params'; pwd; ./some_other_action 'other params';"
because it is extremely ugly and difficult to read.
How about a Bash Here Document:
ssh otherhost << EOF
ls some_folder;
./someaction.sh 'some params'
pwd
./some_other_action 'other params'
EOF
To avoid the problems mentioned by #Globalz in the comments, you may be able to (depending what you're doing on the remote site) get away with replacing the first line with
ssh otherhost /bin/bash << EOF
Note that you can do variable substitution in the Here document, but you may have to deal with quoting issues. For instance, if you quote the "limit string" (ie. EOF in the above), then you can't do variable substitutions. But without quoting the limit string, variables are substituted. For example, if you have defined $NAME above in your shell script, you could do
ssh otherhost /bin/bash << EOF
touch "/tmp/${NAME}"
EOF
and it would create a file on the destination otherhost with the name of whatever you'd assigned to $NAME. Other rules about shell script quoting also apply, but are too complicated to go into here.
Edit your script locally, then pipe it into ssh, e.g.
cat commands-to-execute-remotely.sh | ssh blah_server
where commands-to-execute-remotely.sh looks like your list above:
ls some_folder
./someaction.sh
pwd;
To match your sample code, you can wrap your commands inside single or double qoutes. For example
ssh blah_server "
ls
pwd
"
I see two ways:
First you make a control socket like this:
ssh -oControlMaster=yes -oControlPath=~/.ssh/ssh-%r-%h-%p <yourip>
and run your commands
ssh -oControlMaster=no -oControlPath=~/.ssh/ssh-%r-%h-%p <yourip> -t <yourcommand>
This way you can write an ssh command without actually reconnecting to the server.
The second would be to dynamically generate the script, scping it and running.
This can also be done as follows.
Put your commands in a script, let's name it commands-inc.sh
#!/bin/bash
ls some_folder
./someaction.sh
pwd
Save the file
Now run it on the remote server.
ssh user#remote 'bash -s' < /path/to/commands-inc.sh
Never failed for me.
Put all the commands on to a script and it can be run like
ssh <remote-user>#<remote-host> "bash -s" <./remote-commands.sh
Not sure if the cleanest for long commands but certainly the easiest:
ssh user#host "cmd1; cmd2; cmd3"
This works well for creating scripts, as you do not have to include other files:
#!/bin/bash
ssh <my_user>#<my_host> "bash -s" << EOF
# here you just type all your commmands, as you can see, i.e.
touch /tmp/test1;
touch /tmp/test2;
touch /tmp/test3;
EOF
# you can use '$(which bash) -s' instead of my "bash -s" as well
# but bash is usually being found in a standard location
# so for easier memorizing it i leave that out
# since i dont fat-finger my $PATH that bad so it cant even find /bin/bash ..
SSH and Run Multiple Commands in Bash.
Separate commands with semicolons within a string, passed to echo, all piped into the ssh command. For example:
echo "df -k;uname -a" | ssh 192.168.79.134
Pseudo-terminal will not be allocated because stdin is not a terminal.
Filesystem 1K-blocks Used Available Use% Mounted on
/dev/sda2 18274628 2546476 14799848 15% /
tmpfs 183620 72 183548 1% /dev/shm
/dev/sda1 297485 39074 243051 14% /boot
Linux newserv 2.6.32-431.el6.x86_64 #1 SMP Sun Nov 10 22:19:54 EST 2013 x86_64 x86_64 x86_64 GNU/Linux
The posted answers using multiline strings and multiple bash scripts did not work for me.
Long multiline strings are hard to maintain.
Separate bash scripts do not maintain local variables.
Here is a functional way to ssh and run multiple commands while keeping local context.
LOCAL_VARIABLE=test
run_remote() {
echo "$LOCAL_VARIABLE"
ls some_folder;
./someaction.sh 'some params'
./some_other_action 'other params'
}
ssh otherhost "$(set); run_remote"
For anyone stumbling over here like me - I had success with escaping the semicolon and the newline:
First step: the semicolon. This way, we do not break the ssh command:
ssh <host> echo test\;ls
^ backslash!
Listed the remote hosts /home directory (logged in as root), whereas
ssh <host> echo test;ls
^ NO backslash
listed the current working directory.
Next step: breaking up the line:
v another backslash!
ssh <host> echo test\;\
ls
This again listed the remote working directory - improved formatting:
ssh <host>\
echo test\;\
ls
If really nicer than here document or quotes around broken lines - well, not me to decide...
(Using bash, Ubuntu 14.04 LTS.)
The easiest way to configure your system to use single ssh sessions by default with multiplexing.
This can be done by creating a folder for the sockets:
mkdir ~/.ssh/controlmasters
And then adding the following to your .ssh configuration:
Host *
ControlMaster auto
ControlPath ~/.ssh/controlmasters/%r#%h:%p.socket
ControlMaster auto
ControlPersist 10m
Now, you do not need to modify any of your code. This allows multiple calls to ssh and scp without creating multiple sessions, which is useful when there needs to be more interaction between your local and remote machines.
Thanks to #terminus's answer, http://www.cyberciti.biz/faq/linux-unix-osx-bsd-ssh-multiplexing-to-speed-up-ssh-connections/ and https://en.wikibooks.org/wiki/OpenSSH/Cookbook/Multiplexing.
What is the cleanest way to ssh and run multiple commands in Bash?
I recommend using this escaping function. The function takes one argument - a function to escape. Then sshqfunc outputs declare -f of the function and then outputs a string that will call the function with "$#" arguments properly quoted. Then the whole is "%q" quoted and bash -c is added. In case the remote does not have bash, you could change bash to sh.
sshqfunc() { echo "bash -c $(printf "%q" "$(declare -f "$#"); $1 \"\$#\"")"; };
Then define a function with the work you want to do on the remote. The function is defined normally, so it will be properly "clean". You can test such function locally. After defining, properly escaped function is passed to the remote.
work() {
ls
pwd
echo "Some other command"
}
ssh host#something "$(sshqfunc work)"
Passing You can also pass arguments, and they will be passed to your function as positional arguments. The right next argument after the function will be assigned to $0 - usually a placeholder like -- or _ is used to separate arguments from call.
work() {
file=$1
num=$2
ls "$file"
echo "num is $num"
}
ssh host#something "$(sshqfunc work)" -- /this/file 5
But note that arguments should also be properly quoted if there are any magic characters:
ssh host#something "$(sshqfunc work)" -- "$(printf "%q" "$var1" "$var2")"
For simple commands you can use:
ssh <ssh_args> command1 '&&' command2
or
ssh <ssh_args> command1 \&\& command2
I'm trying to execute a tcsh script in a bash environment. My regular environment is tcsh so the following command works for me:
source /usr/scripts/my_setup -t abs
But I need to execute this command from some third party software which runs the commands on bash shell. This script should set an environment variable $TMP.
I already tried all the suggested solutions from the previous threads and they all do not work.
What I tried:
tcsh -c "source /usr/scripts/my_setup -t abs ; exec bash"
tcsh -c "source /usr/scripts/my_setup -t abs ; bash"
The following steps:
echo "tcsh -c 'source /usr/scripts/my_setup -t abs'" > setup
chmod a+x setup
source setup
They all fail. And I understand why (everytime I use tcsh it opens a new shell). But I can't seem to understand how to source a tcsh script from bash.
I'd like to execute several commands in sequence on a remote machine, and some of the later commands depend on earlier ones. In the simplest possible example I get this:
ssh my_server "echo this is my_server; abc=2;"
this is my_server
abc=2: Command not found.
ssh my_server "echo this is my_server; abc=2; echo abc is $abc"
abc: undefined variable
For a bit of background info, what I actually want to do is piece together a path and launch a java application:
ssh my_server 'nohup sh -c "( ( echo this is my_server; jabref_exe=`which jabref`; jabref_dir=`dirname $jabref_exe`; java -jar $jabref_dir/../jabref.jar` $1 &/dev/null ) & )"' &
jabref_dir: Undefined variable.
That way, whenever jabref gets updated to a new version on the server, I won't have to manually update the path to the jar file. The jabref executable doesn't take arguments, but launching it with java -jar does, which is why I have to juggle the path a bit.
At the moment I have the list of commands in a separate script file and call
ssh my_server 'nohup sh -c "( ( my_script.sh &/dev/null ) & )"' &
which works, but since the ssh call is already inside one script file it would be nice to have everything together.
In this example
ssh my_server "echo this is my_server; abc=2;"
abc is set on the remote side, so it should be clear why it is not set on your local machine.
In the next example,
ssh my_server "echo this is my_server; abc=2; echo abc is $abc"
your local shell tries to expand $abc in the argument before it is ever sent to the remote host. A slight modification would work as you expected:
ssh my_server 'echo this is my_server; abc=2; echo abc is $abc'
The single quotes prevent your local shell from trying to expand $abc, and so the literal text makes it to the remote host.
To finally address your real question, try this:
jabref_dir=$( ssh my_server 'jabref_exe=$(which jabref); jabref_dir=$(dirname $jabref_exe);
java -jar $jabref_dir/../jabref.jar > /dev/null; echo $jabref_dir' )
This will run the quoted string as a command on your remote server, and output exactly one string: $jabref_dir. That string is captured and stored in a variable on your local host.
With some inspiration from chepner, I now have a solution that works, but only when called from a bash shell or bash script. It doesn't work from tcsh.
ssh my_server "bash -c 'echo this is \$HOSTNAME; abc=2; echo abc is \$abc;'"
Based on this, the code below is a local script which runs jabref on a remote server (although with X-forwarding by default and passwordless authentication the user can't tell it's remote):
#!/bin/bash
if [ -f "$1" ]
then
fname_start=$(echo ${1:0:4})
if [ "$fname_start" = "/tmp" ]
then
scp $1 my_server:$1
ssh my_server "bash -c 'source load_module jdk; source load_module jabref; java_exe=\$(which java); jabref_exe=\$(which jabref); jabref_dir=\$(echo \${jabref_exe%/bin/jabref});eval \$(java -jar \$jabref_dir/jabref.jar $1)'" &
else
echo input argument must be a file in /tmp.
else
echo this function requires 1 argument
fi
and this is the 1-line script load_module, since modulecmd sets environment variables and I couldn't figure out how to do that without sourcing a script.
eval `/path/to/modulecmd bash load $1`;
I also looked at heredocs, inspired by How to use SSH to run a shell script on a remote machine? and http://tldp.org/LDP/abs/html/here-docs.html. The nice part is that it works even from tcsh. I got this working from the command line, but not inside a script. That's probably easy enough to fix, but I've got a solution now so I'm happy :-)
ssh my_server 'bash -s' << EOF
echo this is \$HOSTNAME; abc=2; echo abc is \$abc;
EOF
When I run the following from my bash shell:
bash -c '(export abc=123 && echo $abc)'
The output is "123". But when I run it over ssh:
ssh remote-host "bash -c '(export abc=123 && echo $abc)'"
There is no output. Why is this? Is there a way around this? That is, is there a way to set an environment variable for a command I run over ssh?
Note: When I replace echo $abc with something standard like echo $USER the ssh command prints out the username on the remote machine as expected since it is already set.
I am running RHEL 5 Linux with OpenSSH 4.3
That is because when using
ssh remote-host "bash -c '(export abc=123 && echo $abc)'"
the variable gets expanded by the local shell (as it is the case with $USER) before ssh executes. Escape the $ by using \$ and it should do fine
ssh remote-host "bash -c '(export abc=123 && echo \$abc)'"
On a side note:
You don't need to export just for this.
You don't need to wrap it in ()
Like so:
ssh remote-host "bash -c 'abc=123 && echo \$abc'"
Heck, you can even leave out the bash -c ... stuff, as the ssh manpage states:
If command is specified, it is executed on the remote host instead of a login shell.
But these may be specific to your task ;)
I'd like to execute several commands in sequence on a remote machine, and some of the later commands depend on earlier ones. In the simplest possible example I get this:
ssh my_server "echo this is my_server; abc=2;"
this is my_server
abc=2: Command not found.
ssh my_server "echo this is my_server; abc=2; echo abc is $abc"
abc: undefined variable
For a bit of background info, what I actually want to do is piece together a path and launch a java application:
ssh my_server 'nohup sh -c "( ( echo this is my_server; jabref_exe=`which jabref`; jabref_dir=`dirname $jabref_exe`; java -jar $jabref_dir/../jabref.jar` $1 &/dev/null ) & )"' &
jabref_dir: Undefined variable.
That way, whenever jabref gets updated to a new version on the server, I won't have to manually update the path to the jar file. The jabref executable doesn't take arguments, but launching it with java -jar does, which is why I have to juggle the path a bit.
At the moment I have the list of commands in a separate script file and call
ssh my_server 'nohup sh -c "( ( my_script.sh &/dev/null ) & )"' &
which works, but since the ssh call is already inside one script file it would be nice to have everything together.
In this example
ssh my_server "echo this is my_server; abc=2;"
abc is set on the remote side, so it should be clear why it is not set on your local machine.
In the next example,
ssh my_server "echo this is my_server; abc=2; echo abc is $abc"
your local shell tries to expand $abc in the argument before it is ever sent to the remote host. A slight modification would work as you expected:
ssh my_server 'echo this is my_server; abc=2; echo abc is $abc'
The single quotes prevent your local shell from trying to expand $abc, and so the literal text makes it to the remote host.
To finally address your real question, try this:
jabref_dir=$( ssh my_server 'jabref_exe=$(which jabref); jabref_dir=$(dirname $jabref_exe);
java -jar $jabref_dir/../jabref.jar > /dev/null; echo $jabref_dir' )
This will run the quoted string as a command on your remote server, and output exactly one string: $jabref_dir. That string is captured and stored in a variable on your local host.
With some inspiration from chepner, I now have a solution that works, but only when called from a bash shell or bash script. It doesn't work from tcsh.
ssh my_server "bash -c 'echo this is \$HOSTNAME; abc=2; echo abc is \$abc;'"
Based on this, the code below is a local script which runs jabref on a remote server (although with X-forwarding by default and passwordless authentication the user can't tell it's remote):
#!/bin/bash
if [ -f "$1" ]
then
fname_start=$(echo ${1:0:4})
if [ "$fname_start" = "/tmp" ]
then
scp $1 my_server:$1
ssh my_server "bash -c 'source load_module jdk; source load_module jabref; java_exe=\$(which java); jabref_exe=\$(which jabref); jabref_dir=\$(echo \${jabref_exe%/bin/jabref});eval \$(java -jar \$jabref_dir/jabref.jar $1)'" &
else
echo input argument must be a file in /tmp.
else
echo this function requires 1 argument
fi
and this is the 1-line script load_module, since modulecmd sets environment variables and I couldn't figure out how to do that without sourcing a script.
eval `/path/to/modulecmd bash load $1`;
I also looked at heredocs, inspired by How to use SSH to run a shell script on a remote machine? and http://tldp.org/LDP/abs/html/here-docs.html. The nice part is that it works even from tcsh. I got this working from the command line, but not inside a script. That's probably easy enough to fix, but I've got a solution now so I'm happy :-)
ssh my_server 'bash -s' << EOF
echo this is \$HOSTNAME; abc=2; echo abc is \$abc;
EOF