Exerpt from bash documentation. HISTORY EXPANSION The bash shell supports a history expansion feature that is similar to the history expansion in csh. This feature is enabled by default for interactive shells, and can be disabled using the +H option to the set builtin command. Non-interactive shells do not perform history expansion by default. History expansions introduce words from the history list into the input stream, making it easy to repeat commands, insert the arguments to a previous command into the current input line, or fix errors in previous commands quickly. History expansion is performed immediately after a complete line is read, before the shell breaks it into words. It takes place in two parts. The first is to determine which line from the history...

An XML schema is a definition of XML files, in XML. It plays the same role as old-time DTDs. Overall, an XML schema file looks like this: <schema attributeFormDefault = (qualified | u... The attribute meanings: targetNamespace : The name space targeted by the current schema definition. It can be any URI. id and version : For user convenience, the W3C spec defines no semantics for them. xml:lang : Natural language identifier defined by RFC 3306 . attributeFormDefault and elementFormDefault : Set default values for the form attribute for attribute and element declarations. blockDefault and finalDefault : Set default values for the block and final attributes for attribute and element declarations. The W3C defined some built-in datatypes . Examples of primitive datatypes are: string ,...

Lyx wasn't able to open DVI files with the error message MIME type application/x-dvi not supported. I looked at Lyx preferences and it's using xdg-open to open the file. The following query shows that the default application for the DVI mime type is Evince. So I updated that to xdvi , which I do have. $ xdg-mime query default application/x-dvi ... But it didn't work! I checked that the file ~/.local/share/applications/defaults.list did get updated. I even logged out and logged back in! I had to update the system wide configuration file /usr/share/applications/defaults.list to make it work: #application/x-dvi=evince.desktop applicati...

cURL is a command line tool for transferring files with URL syntax. The main purpose and use for cURL is to automate unattended file transfers or sequences of operations. It's really easy to see HTTP headers with curl: C:\>curl --head http://www.google.com HTTP/1.0 ... or, headers and page together (dump headers to stdout): $ curl --dump-header - http://www.google.com HTTP/... Download openssl from openssl.org: curl http://www.openssl.org/source/openssl-0.9.6m.... C:\>curl --help Usage: curl [options...] <url> ...

On Linux, you can use the fuser command to find out who has a file open, or is using a port. For example, if you start Tomcat and get the error "Address already in use: 8080", you want to know which process is already binding to port 8080. # list processes on port 8080 fuser 8080/tcp ...

I installed vncserver on my Fedora box and tried to connect to it with vncviewer from Windows XP. I got this error: What could be the problem? These were the steps I took to diagnose it. I just list them here as a reminder. Is Windows firewall blocking the connection? No. It turned out that, unlike ZoneAlarm , the Windows firewall does not block outgoing traffic. It only blocks incoming requests. Is vncserver listening on the right IP address? Yes. netstat showed it's listening on all NICs. netstat -a | grep 5901 tcp 0 0 *:59... Is VNC port open on the local Fedora box on that IP address? Yes, telnet successfully connected: [jim@fedora ~] telnet 172.30.33.9 5901 Trying 1... What does telnet say from...

Suppose you have a file with these lines: -- contents of update_contact.sql update co... You can execute this script from the SQL prompt by entering: @update_contact.sql And it would execute fine. Now you get the contents of the script into the SQL buffer by: GET update_contact.sql and use the / command to execute the buffer, you get ORA-00911 invalid character error for the semicolon at the first line. Confusing, right? It turned out that the semicolon is used by SQL*Plus to signify the end of a SQL command. When you enter SQL commands into SQL*Plus, it strips the trailing semicolon before sending the SQL command to the database. But when you import the contents of a file with the GET command, the semicolon is...