I am trying to execute a bash shell that calls the mongo shell with a command created dynamically. The bash shell looks like this:
#!/bin/bash
TODAY=`date '+%Y-%m-%d'`
CMD=" 'printjson(db.collection.aggregate([{$match:{processedtime:{$gte:\"$TODAY"}}},{$project:{_id:$field",count:{$sum:1}}}]))'"
echo "CMD: $CMD"
mongo host/mdb --eval $CMD
Note the processedtime field in the collection is a sting value formatted as an ISODate object.
When executed as a bash shell I get an "Unexpected token ILLEGAL" error. If I execute the command echoed to the screen I get the desired results.
My question is, Is there a way to pass in shell defined variables into the mongo shell and if there is what do I need to change to do this?
You're note escaping enough, and I believe you don't want the literal single quotes:
CMD="printjson(db.collection.aggregate([{\$match:{processedtime:{\$gte:\"$TODAY\"}}},{\$project:{_id:\$field",count:{\$sum:1}}}]))"
# ...^.. single quote unneeded ..........^.......................^.....^.......&......^..............^...............^............^
mongo host/mdb --eval "$CMD"
# ....................^....^ crucial double quotes here
Related
I want to log into server based on user's choice so I wrote bash script. I am totally newbie - it is my first bash script:
#!/bin/bash
echo -e "Where to log?\n 1. Server A\n 2. Server B"
read to_log
if [ $to_log -eq 1 ] ; then
echo `ssh user#ip -p 33`
fi
After executing this script I am able to put a password but after nothing happens.
If someone could help me solve this problem, I would be grateful.
Thank you.
The problem with this script is the contents of the if statement. Replace:
echo `ssh user#ip -p 33`
with
ssh user#ip
and you should be good. Here is why:
Firstly, the use of back ticks is called "command substitution". Back ticks have been deprecated in favor of $().
Command substitution tells the shell to create a sub-shell, execute the enclosed command, and capture the output for assignment/use elsewhere in the script. For example:
name=$(whoami)
will run the command whoami, and assign the output to the variable name.
the enclosed command has to run to completion before the assignment can take place, and during that time the shell is capturing the output, so nothing will display on the screen.
In your script, the echo command will not display anything until the ssh command has completed (i.e. the sub-shell has exited), which never happens because the user does not know what is happening.
You have no need to capture the output of the ssh command, so there is no need to use command substitution. Just run the command as you would any other command in the script.
As an example, I am trying to capture the raw commands that are output by the following script:
https://github.com/adampointer/go-deribit/blob/master/scripts/generate-models.sh
I have tried to following a previous answer:
BASH: echoing the last command run
but the output I am getting is as follows:
last command is gojson -forcefloats -name="${struct}" -tags=json,mapstructure -pkg=${p} >> models/${p}/${name%.*}_request.go
What I would like to do is capture the raw command, in other words have variables such as ${struct}, ${p} and ${p}/${name%.*} replaced by the actual values that were used.
How do I do this?
At the top of the script after the hashbang #!/usr/bin/env bash or #!/bin/bash (if there is any) add set -x
set -x Print commands and their arguments as they are executed
Run the script in debug mode which will trace all the commands in the script: https://stackoverflow.com/a/10107170/988525.
You can do that without editing the script by typing "bash generate-models.sh -x".
I'm writing a script that would give me an ability to execute other local bash scripts remotely over SSH without uploading them. Some of my servers have Linux, some FreeBSD with csh as default. So far, I've came to the following:
ssh remote_server 'bash -c '\'"$(cat local_script.sh)"\'' script_parameters'
This allows me to execute local_script.sh on remote_server, supports interactivity (for example, "read" command will work in local_script.sh), and I can transfer positional parameters to the script. The problem is that if a local_script.sh has multiple lines the code above works for remote servers with bash default shell only. On FreeBSD sshd starts csh first to execute "bash -c" command and tries to pass the script code (the result of $(cat local_script.sh)) to it as the first parameter. But because this code is multiline and csh wants the closing quote be on the same line as the opening quote I get the "Unmatched '." error. So csh just can't parse this escaped multiline parameter to pass it to the bash process.
The only solution I can see now is to parse the local_script.sh and automatically rewrite it into a one-liner using ";" delimiters before passing it via SSH. But this requires creating another script and seems to be not so easy. So I'd like to ask if this csh miltiline parsing problem can be resolved somehow?
What about using standard input /dev/stdin ?
ssh remote_server bash /dev/stdin script_parameters < local_script.sh
Using two different commands and temporary file
bash
ssh remote_server $'tmp=`mktemp tmp.XXXXXX`;cat <<\'HEREDOC_END\' >"$tmp"
'"$(cat local_script.sh)"'
HEREDOC_END
bash "$tmp" script_parameters ;rm "$tmp"'
csh
ssh remote_server 'set tmp=`mktemp tmp.XXXXXX`;cat <<"HEREDOC_END" >"$tmp"
'"$(cat local_script.sh)"'
"HEREDOC_END"
bash "$tmp" script_parameters ;rm "$tmp"'
In this particular case, there is no need to keep the outermost quotes.
ssh remote_server bash -c "\"$(cat local_script.sh)\"" script_parameters
This is not entirely robust; for example, single quotes in local_script.sh will not quote text verbatim. So the following example
echo 'fnord "$(echo yes)"'
will have the command substitution evaluated remotely even though the string is in single quotes. In the general case, you'd have to replace cat with, basically, a shell parser which identifies constructs which need escaping.
Below command to set the PS1 doesn't work for me
here is my shell:-
[u#h w]$echo $SHELL
/bin/ksh93
command:-
PS1="[\u#\h \w]\$"
returned output:-
[u#h w]$
Expected output:-
Linux#LinuxDistro /home/sohil$
in ksh \u etc won't work. You have to use something like
PS1='[$(id -un)#$(hostname -s) $PWD]$ '
Use single quotes, otherwise the prompt will not change with each command.
Or if you want to always show the initial user and hostname
PS1="[$(whoami)#$(hostname -s) \$PWD]$ "
I am writing a simple bash script (checkServs.sh) that will ssh into a list of servers and perform a health check on them.
I keep getting errors on the following line:
SERVERS=(blah1.example.com blah2.example.com blah3.example.com blah4.example.com)
Error is:
checkServs.sh: 3: checkServs.sh: Syntax error: "(" unexpected
I've checked online examples and this seems correct, isn't it? Thanks in advance!
I don't know about the syntax error, but this should work:
SERVERS="blah1.example.com blah2.example.com blah3.example.com blah4.example.com"
for server in $SERVERS
do
echo $server
done
EDIT: As noted by Jonathan Leffler in a comment, maybe you are not running the script with bash. Other shells, such as dash, may not recognize the array syntax. If that's the case, you can do:
SERVERS=(blah1.example.com blah2.example.com blah3.example.com blah4.example.com)
for i in $(seq 0 3)
do
echo ${SERVERS[$i]}
done
But if you just want to loop through the names and run an SSH command (ie if having an array won't provide useful functionality), the first method is more straightforward.
Your remote server probably calls a different shell when executing commands. Try to add bash -c to your arguments:
ssh user#server bash -c "<your commands>"
Or:
ssh user#server bash < yourscript.sh ## None in yourscript.sh must read input though.
An opening parenthesis starts a subshell, which is not a correct thing to have on the right side of an equals sign. It expects a string expression, not a command.
Quotation marks are used to keep a string expression together.