I'm using a big-data database. in one of it's tutorial it has recommended me to use below bash scripts if order to running queries:
#!/bin/sh
# this will launch the real atquery program with the given .sql file
# note: please adjust INSTALLNAME, HOST and PORT to reflect your installation
/home/lms/INSTALLNAME/atquery HOST:PORT $*
Then, start runnable .sql files like the following:
#!/usr/local/bin/runatquery
select count(*) from mytable during all
I don't understand $* part of the /home/lms/INSTALLNAME/atquery HOST:PORT $*. what will $* does?
this was suppose to create a shell script in order to run a query, but another problem is this is two file (I supposse because we two #! in that) so how will this two file help me to run queries? I suppose if we had a script with below code in it, it would do this work to me better and without confusion:
!/bin/sh
/home/lms/INSTALLNAME/atquery HOST:PORT -e 'select count(*) from mytable during all'
You have to create that script as recommended (you didn't include that, probably right before the script) as a file with the executable bit on, and changing INSTALLNAME, HOST and PORT as per your system requirements.
The $* expands to all parameters received by the script.
The second file is an example of how you can create scripts that are run by runatquery.
Related
When creating Bash scripts, I have always had a line right at the start defining the PATH environment variable. I recently discovered that this doesn't make the script very portable as the PATH variable is different for different versions of Linux (in my case, I moved the script from Arch Linux to Ubuntu and received errors as various executables weren't in the same places).
Is it possible to copy the PATH environment variable defined by the login shell into the current Bash script?
EDIT:
I see that my question has caused some confusion resulting in some thinking that I want to change the PATH environment variable of the login shell with a bash script, which is the exact opposite of what I want.
This is what I currently have at the top of one of my Bash scripts:
#!/bin/bash
PATH=/usr/local/sbin:/usr/local/bin:/usr/bin:/usr/bin/site_perl:/usr/bin/vendor_perl:/usr/bin/core_perl
# Test if an internet connection is present
wget -O /dev/null google.com
I want to replace that second line with something that copies the value of PATH from the login shell into the script environment:
#!/bin/bash
PATH=$(command that copies value of PATH from login shell)
# Test if an internet connection is present
wget -O /dev/null google.com
EDIT 2: Sorry for the big omission on my part. I forgot to mention that the scripts in question are being run on a schedule through cron. Cron creates it's own environment for running the scripts which does not use the environment variables of the login shell or modify them. I just tried running the following script in cron:
#!/bin/bash
echo $PATH >> /home/user/output.txt
The result is as follows. As you can see, the PATH variable used by cron is different to the login shell:
user#ubuntu_router:~$ cat output.txt
/usr/bin:/bin
user#ubuntu_router:~$ echo $PATH
/usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin:/usr/games:/usr/local/games
Don't touch the user's PATH at all unless you have a specific reason. Not doing anything will (basically) accomplish what you ask.
You don't have to do anything to get the user's normal PATH since every process inherits the PATH and all other environment variables automatically.
If you need to add something nonstandard to the PATH, the usual approach is to prepend (or append) the new directory to the user's existing PATH, like so:
PATH=/opt/your/random/dir:$PATH
The environment of cron jobs is pretty close to the system's "default" (for some definition of "default") though interactive shells may generally run with a less constrained environment. But again, the fix for that is to add any missing directories to the current value at the beginning of the script. Adding directories which don't exist on this particular system is harmless, as is introducing duplicate directories.
I've managed to find the answer to my question:
PATH=$PATH:$(sed -n '/PATH=/s/^.*=// ; s/\"//gp' '/etc/environment')
This command will grab the value assigned to PATH by Linux from the environment file and append it to the PATH used by Cron.
I used the following resources to help find the answer:
How to grep for contents after pattern?
https://help.ubuntu.com/community/EnvironmentVariables#System-wide_environment_variables
I have 2 DB2 sql scripts that I need to run. I have tried to put both of them in bash script and execute them.
here is script.sh:
#!/bin/bash
db2 -tf firstscript.sql;
db2 -tf secondscript.sql;
When I run this, I get the following error:
DB21034E The command was processed as an SQL statement because it was
not a valid Command Line Processor command. During SQL processing it
returned: SQL1024N A database connection does not exist.
SQLSTATE=08003
But I have made sure that the database connection already exists.
I think that the commands inside the sql scripts are not executed sequentially.
Because when I run each command individually, there is no error.
Also, when I run both the commands inline i.e. db2 -tf firstscript.sql;db2 -tf firstscript.sql, even then the code works.
I thought that it could have something to do with #!/bin/bash, so I removed it from the script.sh file and then executed it. Even then, it returned the same error.
What would be the possible problem and its solution?
When you have a establish connection, it is hold in your current environment. When you call a bash script, it will create a subshell, and that will not have any connection.
In order to solve this problem, you need to reuse the current environment by sourcing the script (as #jm666 said):
. ./script.sh
Make sure about the dot followed by a space before the scriptname.
db2 connect to sample
. ./script.sh
FYI, the commands inside the script will be executed sequentially, as you defined them.
The problem that I am having is that I want to run the following command (and I can't):
cqlsh < cql_directory/cql_create_stuff.cql
Because I have not logged in to cqlsh.
So I logged in:
cqlsh -u 'my_username' -p 'my_super_secret_password'
and now I tried doing the command in cqlsh shell but It just responds with a syntax error.
Basically, how do I login into cqlsh and run an external CQL script in my file system?
Use the SOURCE
http://www.datastax.com/documentation/cql/3.1/cql/cql_reference/source_r.html
You can use -f option as well to execute commands from file
http://www.datastax.com/documentation/cql/3.1/cql/cql_reference/cqlsh.html
Assuming that the path of the file with the CQL commands is /mydir/myfile.cql, there are two ways:
If you are not logged in to cqlsh:
cqlsh -u 'my_username' -p 'my_password' -f /mydir/myfile.cql
If you are logged in to cqlsh:
SOURCE '/mydir/myfile.cql'
Notice the single quotation marks. The shorthand notation for $HOME (for example, '~/mydir/myfile.cql') is also supported.
Both ways also work with relative paths (to the current directory).
Assuming your filename is "tables.cql" and it is placed as: /files/tables.cql;
A - Locally
cqlsh -f /files/tables.cql
B - Connecting To A Docker Container Running Cassandra
Assuming the name of the Docker container that which running Cassandra is "cas" (keep in mind that you can also use the hash id of the docker container if there is no name assigned to it);
docker exec -it cas cqlsh -f /files/tables.cql
As stated on other answers, -u and -p options can be added in order to use the username/password combinations.
This is for Window system
suppose you cassandra dir is
C:\Program Files\DataStax-DDC\apache-cassandra\bin
Suppose directory where your .cql file OR cql query file is
D:\ril\s\developement\new one\excel after parse\Women catalogue template.cql
Now follow below steps for importing cql file
Go on command prompt (cmd)
Go on the directory where cql file is there (cd "..\ril\sizeguide\developement\new one\excel after parse")
Run below command
"c:\Program Files\DataStax-DDC\apache-cassandra\bin\cqlsh.bat" <"Women catalogue template.cql"
And its Done.
Important Note:
Please make sure column value should not have single quote ' character like ('If you don't find a exact match, go for the next large size') other wise it will fail.
If you want single quote to be inserted, please use it two times like below and Cassandra will treat it as one time
('If you don''t find a exact match, go for the next large size')
All text column should be enclosed by single quote '' like 'Sale category'. For empty value, please use two single quote ''.
I (on mac osx) often use
export http_proxy=http://192.168.0.205:1099
to proxy http connection to get a highed download speed. To make things easy， I wrote a shell file named proxy.sh to do this:
#!/bin/sh
export http_proxy=http://192.168.0.205:1099
Before I downlaod, I execute proxy.sh shell command, but I found it did't not come into effect.It lost http_proxy variable in current commnad window(terminal). I must type export command in current terminal,it will come into effect.
So I want to know what's reason for this and a solution? thanks.
Running a shell script "normally" (with proxy.sh for example) results in that running in a sub-process so that it cannot affect the environment of the parent process.
Using . or source will run the shell script in the context of the current shell, so it will be able to affect the environment, using one of the following:
. proxy.sh
source proxy.sh
Another possibility (if you're using bash at least) is to create an alias to do the work for you. You can use something like:
alias faster='export http_proxy=http://192.168.0.205:1099'
so that you can then simply type faster on the command line and it will export that variable (in the context of the current shell).
You could also allow for one-shot settings such as:
alias faster='http_proxy=http://192.168.0.205:1099'
and then use:
faster your_program
which would translate into:
http_proxy=http://192.168.0.205:1099 your_program
That's a bash way to set a variable for just the one invocation of a command.
The export variable will only apply to the script -- if you want it to apply to the shell, you need to use source, and execute the script like so:
. ./proxy.sh
or:
source ./proxy.sh
Note the "." in the first example -- the dot follow by space means the script will apply to the shell.
The reason why your script does not work has been explained by Drakosha & how to make your script work has been explained by Anothony. But with the export in the script you need to source your script each time you open a new terminal. A better solution will be to add the export in .bash_profile or .bashrc
Hope this helps!
When executing a shell script a new shell is launched, the script is executed, and the shell dies. That's why you don't see the variable defined in your shell.
I suggest using an alias for the same purpose.
I have tried exporting my paths and variables and crontab still will not run my script. I'm sure I am doing something wrong.
I have a shell script which runs a jar file. This is not working correctly.
After reading around I have read this is commonly due to incorrect paths due to cron running via its own shell instance and therefore does not have the same preferences setup as my profile does.
Here is what my script looks like today after several modifications:
#!/bin/bash --
. /root/.bash_profile
/usr/bin/java -jar Pharmagistics_auto.jar -o
...
those are the most important pieces of the script, the rest are straightforward shell based.
Can someone tell me what I am doing wrong?
Try specifying the full path to the jar file:
/usr/bin/java -jar /path/to/Pharmagistics_auto.jar -o
I would just tell you what you have already ruled out: Check your path and environment.
Since you have alredy done this, start debugging. Like write checkpoints into a logfile to see how far your script gets (if even started at all), check the cronjob log file for errors, check your mail (cron sends mails on errors) and so on ...
Not very specific, sorry.
"exporting my paths and variables" won't work since crontab runs in a different shell by a different user.
Also, not sure if this is a typo in how you entered the question, but I see:
usr/bin/java
...and I can't help but notice you're not specifying the fully qualified path. It's looking for a directory named "usr" in the current working directory. Oft times for crontab, the cwd is undefined, hence your reference goes nowhere.
Try specifying the full path from root, like so:
/usr/bin/java
Or, if you want to see an example of relative pathing in action, you could also try:
cd /
usr/bin/java
A few thoughts.
Remove the -- after the #!/bin/bash
Make sure to direct script output seen by cron to mail or somewhere else where you can view it (e.g. MAILTO=desiredUser)
Confirm that your script is running and not blocked by a different long-running script (e.g. on the second line, add touch /tmp/MY_SCRIPT_RAN && exit)
Debug the script using set -x and set -v once you know it's actually running
Do you define necessary paths and env vars in your personal .profile (or other script)? Have you tried sourcing that particular file (or is that what you're doing already with /root/.bash_profile?)
Another way of asking this is: are you certain that whatever necessary paths and env vars you expect are actually available?
If nothing else, have you tried echo'ing individual values or just using the "env" command in your script and then reviewing the stdout?
provide full paths to your jar file, and what user are you running the crontab in? If you set it up for a normal user, do you think that user has permission to source the root's profile?