Have you ever downloaded/uploaded a file from/to another computer and wanted to verify the integrity of the file to make sure it is not corrupted. The obvious way is to compare the file size of the original final and the copied file. However there are many ways that this number could mislead you.
Just to give two examples, in some cases the program you use to download/upload the file can fail to fill in all the data and just pad the file to the correct size. Hardware errors such as disk and memory issues can cause corruptions too that won't effect the file size. So how do you make sure your file is not corrupted and check the integrity of your downloaded/uploaded file.
On Linux/Unix you can use md5sum. The way to use it is to simply run :
md5sum [yourfile]
This prints out something like :
16295afa0087ef75f33751cf003da993 [yourfile]
You will need to run the above command on both the origin of the file and it's destination and compare the digital fingerprint of the file printed. For unique files that fingerprint will be the same.
A lot of websites that let users download files ( specially large files which have a higher chance of getting corrupted in transit ) will provide checksums for their files which you can compare against your when you download is done.
Fixing "authentication is required to set the network proxy ..." on Redhat/REL/OEL
Whenever i started a vncsession i would get an popup window stating :
I didn't have the root password for this machine and hitting cancel would just bring back the pop-up in a few minutes. After googling here is the best way i found to fix this problem:
From a terminal window run "gnome-session-properties" and un-check "PackageKit
Update Applet"
Finally restart your vncserver and the issue should be gone.
authentication is required to set the network proxy used for downloading packages. An
application is attempting to perform an action that requires privileges.
Authentication as the super user is required to perform this action" and asking
for the root password.
I didn't have the root password for this machine and hitting cancel would just bring back the pop-up in a few minutes. After googling here is the best way i found to fix this problem:
From a terminal window run "gnome-session-properties" and un-check "PackageKit
Update Applet"
Finally restart your vncserver and the issue should be gone.
Fixing "Firefox is already running" error in Linux
If you are on Linux and you get the following error when trying to start Firefox, read on for a solution:
This error usually is not solvable with killing the Firefox process, since you won't find one in the list of the current processes.
So how do we get around it?
First, you need to go to your profile directory.
If you have this problem occurring often like me, put the above command in a shell script for more convenience.
Firefox is already running, but is not responding. To open a new window, you must first close the existing Firefox process, or restart your system.
This error usually is not solvable with killing the Firefox process, since you won't find one in the list of the current processes.
So how do we get around it?
First, you need to go to your profile directory.
- cd ~/.mozilla/firefox/[your_profile]
- rm lock
- rm .parentlock
If you have this problem occurring often like me, put the above command in a shell script for more convenience.
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