Commands using finger (6)

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Set laptop display brightness
Run as root. Path may vary depending on laptop model and video card (this was tested on an Acer laptop with ATI HD3200 video). $ cat /proc/acpi/video/VGA/LCD/brightness to discover the possible values for your display.

Find files changed between dates defined by ctime of two files specified by name
This command finds all the files whose status has changed between the ctime of the older and newer . Very useful if you can see from an ls listing a block of consecutive files you want to move or delete, but can't figure out exactly the time range by date.

Find
A lot of X applications accept --geometry parameter so that you can set application size and position. But how can you figure out the exact arguments for --geometry? Launch an application, resize and reposition its window as needed, then launch xwininfo in a terminal an click on the application window. You will see some useful window info including its geometry.

write by vim need root privilege

vi case insensitive search

Keep a copy of the raw Youtube FLV,MP4,etc stored in /tmp/
Certain Flash video players (e.g. Youtube) write their video streams to disk in /tmp/ , but the files are unlinked. i.e. the player creates the file and then immediately deletes the filename (unlinking files in this way makes it hard to find them, and/or ensures their cleanup if the browser or plugin should crash etc.) But as long as the flash plugin's process runs, a file descriptor remains in its /proc/ hierarchy, from which we (and the player) still have access to the file. The method above worked nicely for me when I had 50 tabs open with Youtube videos and didn't want to have to re-download them all with some tool.

(Debian/Ubuntu) Discover what package a file belongs to
'dpkg -S' just matches the string you supply it, so just using 'ls' as an argument matches any file from any package that has 'ls' anywhere in the filename. So usually it's a good idea to use an absolute path. You can see in the second example that 12 thousand files that are known to dpkg match the bare string 'ls'.

Create arbitrary big file full of zeroes but done in a second
If you want to create fast a very big file for testing purposes and you do not care about its content, then you can use this command to create a file of arbitrary size within less than a second. Content of file will be all zero bytes. The trick is that the content is just not written to the disk, instead the space for it is somehow reserved on operating system level and file system level. It would be filled when first accessed/written (not sure about the mechanism that lies below, but it makes the file creation super fast). Instead of '1G' as in the example, you could use other modifiers like 200K for kilobytes (1024 bytes), 500M for megabytes (1024 * 1024 bytes), 20G for Gigabytes (1024*1024*1024 bytes), 30T for Terabytes (1024^4 bytes). Also P for Penta, etc... Command tested under Linux.

Read null character seperated fields from a file
Handle any bad named file which contains ",',\n,\b,\t,` etc Store the file name as null character separated list $find . -print0 >name.lst and retrieve it using $read -r -d "" Eg: $find . -print0 >name.lst; $cat name.lst| while IFS="" read -r -d "" file; $do $ls -l "$file"; $done

list block devices
Shows all block devices in a tree with descruptions of what they are.


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