Skip to main content


Showing posts from 2011

Delete or Change Workplaces and Schools On Facebook Timeline (1/2012 edition)

Have a school or workplace in your Timeline you want to get rid of or change? Here is the method that worked for me. Log into Facebook. Click Profile. On your Timeline, click "Update Info". Under "Work and Education", click the "Edit" button in the upper right hand corner of the section. Each workplace and school will get a box. In the upper right-hand portion of each box, there is an "Edit" link and a small "x". Click the "x" and confirm your choice to delete a workplace or school. Click "Edit" to change the workplace or school.

Getting pictures in focus with a DSLR (digital SLR) in a nutshell.

Higher-end cameras have a number demarcated by the letter "F" that one can set to change the size of the opening (called the iris) that lets light onto the sensor. High numbers make the iris smaller. Optical physics aside, the higher the number, the more of the picture will be in focus and the more light you will need. Likewise, the higher the shutter speed, the more will be frozen in time and the more light you will need as well. So, if you want to capture something that moves fast and have it completely in focus, you need a ton of light, a high F number and a high shutter speed number. Note that a particular lens only supports a particular range of F numbers (called F-stops). You don't have a huge amount of light usually. So you have to find ways to compromise and/or cheat. One way to do this is to use a flash, but that can scare butterflies. Another way is to set the camera to do more processing. This number is demarcated by "ISO". My SLR goes from 200 ISO t

A note of caution: Password Checking Sites.

  Recently, several people have sent me links to check the strength of my password like this: . There is a saying today that if you are not paying for a product, you are the product. Since I haven't seen any independent organization that has audited the code of these sites to prove that they are not also collecting passwords, we must trust that they do not keep copies the entered passwords or their hashes. Either these sites all have a large amount of altruism, or they are creating the most precise rainbow tables [1] available on the market.  There's nothing like doing statistical analysis on a general rainbow table with real passwords to hone its accuracy. Placing blind trust in a 3rd party with one's passwords is never a good idea. I don't think any bank representative would recommend typing one's account password into an un-audited website to check its strength.   If you run one of these sites and have had such an audit, please

How do I convert spaces to underscores in file names and directory names on Linux?

Have you ever wanted to change all the spaces to underscores in a directory?  After going through various methods, the following is the most reliable way that I have found for bash users. Note, that there are many ways to accomplish this task. These examples should be typed in as a single line : find . -depth -maxdepth 1 -name "* *" -exec sh -c 'mv "${0}" "${0// /_}"' {} \; Note that '-maxdepth 1' changes spaces to underscores for files, directories, and links in the current directory. Changing that number to 2 or more will change spaces to underscores two or more levels deep in the current file system tree in addition to the current directory. Leaving out -maxdepth 1 will change spaces to underscores in the entire tree. Note also that the '.' means start in the current directory . You can certainly put other paths in place of the dot.  You can even put what is called a globbing pattern : find music* -depth -maxdepth 1

Linux command line to find all open files...

Useful for restoring deleted files that might be held in memory by a running process: find /proc -type l -wholename "/proc/*/fd/*" -exec ls -l {} \; | egrep -v '.*->.*:.*' Have you ever accidentally deleted an active apache log file while investigating an issue? Backups are useless since the last one was the night before. You may be in luck, though! If there is a running process holding that file in memory, you can get the in-memory copy of the file from /proc on Linux. Run the above command to list files currently held in memory by processes. To restore, copy the "symlink" back to its original location. This will get you the file in the state that the particular process has in memory. The egrep strips out sockets, devices, etc.

Using Google and Bing in Systems Administration - A Brief Note.

Use both search engines Although Microsoft and Google claim that they do not alter search results to promote their interests, they do. It's not necessarily a bad tactic [1]. Just be aware of the behavior. General Steps If you have a general problem, troubleshoot until you have a specific issue/question. If you cannot figure out the answer, run it through both Google and Bing. If you get results, it's either known configuration problem or a known issue with your product. Hopefully there will be a solution. If you get no results, you can generally assume that you are making a common configuration mistake, the solution to which is considered so self-evident that user community of your product doesn't feel it's worth writing up. Re-read your manuals, guides, and tutorials. See the XKCD flowchart for a similar process for family IT problem resolution. No Results At All If you get no results on a specific issue search for a product that is specific to a par

How to fix this ssh error from a Cisco switch: ssh_rsa_verify: RSA modulus too small: 512 < minimum 768 bits

Problem ssh user@cisco_switch returns: ssh_rsa_verify: RSA modulus too small: 512 < minimum 768 bits key_verify failed for server_host_key Solution The modulus of the ssh RSA key pair on the switch is too small. If you have access, generate a new key pair on the switch with a larger modulus. Procedure Login with ssh protocol version 1 ( ssh space dash one ): ssh -1 user@cisco_switch (On the switch): enable (On the switch): Authenticate to "Privileged Exec Mode" mode on the switch. (On the switch): conf t (On the switch): crypto key generate rsa general-keys modulus 1024 (On the switch): Press enter to accept that the current key pair for the switch will be replaced. You now should be able to log into the switch with ssh protocol version 2.