Monday, October 10, 2016
Saturday, July 23, 2016
Friday, July 15, 2016
If you want to experiment some python code as CGI script to serve by a HTTP server, you can get started by these steps:
- Create a
No, really, it's that simple! Try these CGI scripts out.
#!/usr/bin/env python3 localvars_table = '<table>' for x in dir(): localvars_table += '<tr><td>%s</td></tr>' % x localvars_table += '</table>' print("Content-type: text/html") print("") print("""<html><body> <p>Hello World! Your custom CGI script is working. Here are your current Python local variables.</p> %s <p>NOTE: If you want to write useful CGI script, try the Python 'cgi' module. See cgitest.py script.</p> </body></html>""" % (localvars_table))
To test and run this, you simply invoke these couple commands:
bash> chmod a+x cgi-bin/hello.py bash> python3 -m http.server --cgi
You may now test it on your browser with http://localhost:8000/cgi-bin/hello.py. Hit
CTRL+C to stop the server.
If you want to do more with fancy CGI scripts, try the Python's
cgi module. Here is another example.
#!/usr/bin/env python3 import cgi cgi.test()
cgitest.py script and visit http://localhost:8000/cgi-bin/cgitest.py. You will see all the
HTTP related data as expected when working with a CGI script. See https://docs.python.org/3/library/cgi.html
for more details.
Saturday, July 9, 2016
If you have a RedHat/CentOS/OracleLinux distro of Linux, then
yum should be available as your package manager. Here are the notes I have to get PostgreSQL server up running.
bash> yum info postgresql-server bash> # Verify that's the version you want to install bash> # Ready to install bash> sudo su - bash> yum -y install postgresql-server bash> service postgresql initdb bash> # Startup the server manually bash> service postgresql start bash> # Make server startup at system reboot bash> chkconfig postgresql on bash> # Verify postgres DB is working bash> su - postgres -c psql postgres=# \du postgres=# \q bash> # We are done, exit root user shell bash> exit
If you can't find
chkconfig commands, then check to ensure you have have
/sbin in your
Friday, July 8, 2016
Did you know if you have been granted
sudo access to a remote
su command, then you may switch to any user without the
need to type in their password?
Try this out:
zemian@myhost bash> sudo su - postgres # When prompted for password, enter your own user account password. # Now you are in as `postgres` user! postgres@myhost bash>
Or if you want to switch to the root user directly, simply try:
bash> sudo su -
This is very useful when you need to switch to a user account that
was only setup just to run applications (eg:
weblogic etc.) and not intented for real user. In this
case, you might not even know what the real password is. Above
trick should get you switch into that target user account.
Thursday, July 7, 2016
Most of remote systems are secured by SSH, and to gain remote control with terminal, you would need to
ssh into the server. You will be prompted to login with your password on every session. To avoid typing password everytime, you need to setup as authorized client. Here is how you can do that with ssh key.
First on your own client machine, generate the
bash> ssh-keygen # When prompted to enter password, simply hit ENTER key to skip it! bash> cat ~/.ssh/id_rsa.pub xxxyyyzzz zemian@myhost # You will see a very long string instead of "xxxyyyzzz".
Now you need to copy this public key string into your remote host. You need to
ssh into the remote host with your valid password first to setup. If successful, the subsequent
ssh into the remote host will not prompt you for password!
bash> ssh myremotehost # Enter password to gain access
After you are in the remote host:
myremotehost> vim ~/.ssh/authorized_keys #Paste and append the "xxxyyyzzz" into above file.
If you don’t already have the
~/.ssh/authorized_keys file on remote host, then create it, but ensure you don’t let other users or groups to access it. Use command like this to change the permission:
bash> chmod g-rw,o-rw ~/.ssh/authorized_keys
The cool thing about this is that it affects all
ssh related commands, such as
scp will now work without prompting you for password!
Have a productive day!
Wednesday, July 6, 2016
bash> cd $WL_HOME/server/lib bash> keytool -keystore DemoTrust.jks -storepass DemoTrustKeyStorePassPhrase -list bash> keytool -keystore DemoTrust.jks -storepass DemoTrustKeyStorePassPhrase -importcert -alias mycert -file mycert.pem # Or to delete the entry bash> keytool -keystore DemoTrust.jks -storepass DemoTrustKeyStorePassPhrase -delete -alias mycert
mycert.pemcan be obtained by any modern browser when you visit the "https" site. For example using Firefox, you can follow these steps to export the cert file:
Click on the Lock icon next to the URL in the broswer
Click More Information button, then go to the "Security Tab"
Click View Certificate button, then go to the Details tab
Click Export … button
On the bottom right corner dropdown, select X.509 Cerificate with chain (PEM)
Type name of file to save (eg:
mycert.pem) and then click Save button
Tuesday, June 28, 2016
bash> python3.4 -m venv mypy
Error: Command '['/home/zedeng/py-dev/mypy/bin/python3.4', '-Im', 'ensurepip', '--upgrade', '--default-pip']' returned non-zero exit status 1
I found someone posted a nice solution  to this. So first remove the dir first.
bash> rm -r mypy
Now do it again like this:
bash> python3.4 -m venv mypy --without-pip
bash> . mypy/bin/activate
mypy> wget https://bootstrap.pypa.io/get-pip.py
mypy> python get-pip.py
mypy> pip list
Now the problem is solved. I believe this problem is gone if you upgrade to Python 3.5
Monday, June 27, 2016
Installing. If you are running on a Mac, the easiest way to try it out is just get the http://postgresapp.com, you just start the App, and your DB is running! No config needed!
After you have the database installed and running, you can either connect to the default "postgres" public database by (psql command), or create your own database. To create your own database, you run this command:
bash> createdb mydb
Now you can connect to the new database
bash> psql -d mydb
Once you connected to database, you may run SQL to create/insert/select a table:
mydb-# create table test(id serial, name varchar(200));
mydb-# insert into test(name) values('Hello');
mydb-# select * from test;
To inspect your table columns:
mydb-# \d test;
To see all tables available:
To see all database available:
To switch to another database:
mydb-# \c mydb2;
To see more help (check out \d options! it's super flexible and useful.):
To quit the psql shell:
To create a database user and set up password, you can do it on bash shell as well:
Now you may relogin again with the user. It should prompt you for password.
Once you connected to your database again, you may check your user privileges:
These examples should be enough to get you setup a database for app development. The rest are just normal SQL access to database. The PostgresSQL documentation is excellent reference for all that you need: https://www.postgresql.org/docs/9.5/static/index.html
bash> sudo yum install <package_name.rpm>
If you have problem installing it due to gpg check failure and you know it's a good RPM, then try with this.
bash> sudo yum --nogpgcheck localinstall <package_name.rpm>
To verify what's in the rpm:
bash> rpm -qlp <package_name.rpm>
Later I learned that I shouln't track one of IDEA's workspace file, so I want to remove from my repository tracking, but I do not want it be deleted. Here is what you should do:
bash> hg forget .idea/workspace.xml
bash> echo '.idea/workspace.xml' >> .hgignore
Saturday, June 18, 2016
bash> sudo dpkg -i zoom_2.0.52458.0531_amd64.deb
3. Even though the package installed complete, you will see error messages if you have a 64-bit OS because Zoom has other dependencies that's not met. And the above command will setup the apt-get to auto fetch the failed dependencies if you simply run the following next:
bash> sudo apt-get -f install
That's it! Your zoom should be ready to go! Try to start Zoom by press Super + A, then type in "Zoom".
Extra: To Verify Installation, you may run:
bash> dpkg -l |grep zoom
The exact same steps can be used to install the Skype skype-ubuntu-precise_184.108.40.206-1_i386.deb on Ubuntu.
NOTE: If you have errors running steps above, it's very likely you have upgraded your kernel or added extra repositories into apt-get that's causing all the package dependencies conflict. Try to revert back to original Ubuntu 14.04 install state and these steps should get you running!
Friday, June 17, 2016
1. Login to Admin Console (eg: http://localhost:7100/console)
2. On the Domain Structure left panel, click:
<my_domain_name> (eg: DefaultDomain) > Services > Data Sources
3. On the right, Click on the DataSource name you want to test.
4. Click the "Monitoring" tab > "Testing" tab.
5. Select the server the DataSource has targeted to and then press "Test Data Source" button.
Wednesday, June 15, 2016
1. SSH into your remote server and create an empty repository.
bash> cd $HOME
bash> mkdir -p hg-repos/myproject
bash> cd hg-repos/myproject
bash> hg init
2. Back on your local machine and in your existing hg project, edit the .hg/hgrc file with the following:
That's it! You don't even need hg server running in remote host to make this work! Now you may perofrm "hg push" command inside your local project to sync up to remote host
NOTE 1: This setup rely on your SSH into remote host. If you want to avoid user password promt everytime you perform "hg push", then setup Key-Based SSH login.
NOTE 2: You only need "remotecmd" part if your remote_hostname does not have a standard hg installed. Then you can specified your custom location here.
NOTE 3: If you want to use abolute path for "default" path instead, then you can use double slash after the "remote_hostname". Else the single slash is relative to your $HOME directory.