2026-04-26

CD Optical Storage Glossary of Computer Terms (Letter F)

DATARECOVERYUNION.COM23 mins

Fade
A gradual change in brightness of an image or intensity of a sound. Considered a special effect that can be implemented with software or hardware.

File header
A block of data in a file, usually at the beginning, which describes the type of data in the file and the format of the data.

Film scanning
Scalable optical Digitization of photographic transparencies negatives and slides. High quality standards requirements for Pre-press Digitization have resulted in capture specs exceeding 48bpp @ 6000pixels.

Film recording
A service used to produce film transparencies from digital images. Recorder specs, vary from one manufacturer to another near 4000pixels for 35mm film @ 24bpp

Flash memory
Flash memory is a nonvolatile memory medium (it “remembers” even when the power is turned off) that can easily be updated. This credit card-sized package will be used to replace floppy and hard disk drives in portable personal computers in the future. Flash memory cards substantially reduce the computer’s power consumption (when compared with traditional mechanical disk-drive memories).

Flatbed scanning
Document and image scanning utilizing a level glass bed scanner. Device specifications range include RGB @600dpi,single pass

Flicks
Common term for digital motion sequences

Fractal
Fractional Dimensional. A mathematical definition of a fractional element of an image after repeated application of a specific compression algorithm. Has theoretical compression ratio capability of 10,000:1. Commercial software is available with compression ratios in the range of 2,500:1.

Frame
Used in video to denote a complete scan of an image. In motion video repeated scanning ofa changing scene produces a series of frames. Synonymous with a full computer screen desktop applications.

Full-motion video
Display of a video sequence at the broadcast TV frame rate of 30 fps. Sometimes used to define motion video that is perceived to provide smooth motion regardless of frame rate applied.

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Linux Help Commands, Job Management, Process management

DATARECOVERYUNION.COM24 mins

1. Linux Help Commands

Linux management apropos        apropos keyword – Show all commands with the keyword in their description. The same as the “man -k” command.
help        Bash shell help for the bash builtin command list. The help command gets help for a particular command.
man        Get help from the manual for a command.
man        man -k keyword – Show all commands with the keyword in their description
“man 2 kill” – Display page 2 of the kill command
manpath        Determine user’s searchpath for manpages.
info        Documentation on Linux commands and programs similar to the man pages but navigation is organized different.

2. Linux Job Management

at        Similar to cron but run only once.
atq        Lists the user’s pending jobs. If the user is the superuser, everybody’s jobs are listed.
atrm        Deletes at jobs.
atrun        Run jobs queued for later execution
batch        Executes commands when system load levels drop below 0.8 or value specified in atrun invocation.
cron        A deamon used to set commands to be run at specific times. Starts the commands in the crontab file. Used to clean up temporary files periodically in the /var/tmp and /tmp directories.
nice        Run a program with modified scheduling priority.
nohup        Run a command immune to hangups, with output to a non-tty.
watch       Execute a program periodically showing output full screen.

3. Linux Process management

bg        Starts a suspended process in the background
fg         Starts a suspended process in the foreground
gitps        A graphical process viewer and killer program.
jobs        Lists the jobs running
kill        Ex: “kill 34” – Effect: Kill or stop the process with the process ID number 34.
killall        Kill processes by name. Can check for and restart processes.
pidof        Find the process ID of a running program
ps        Get the status of one or more processes. Options:

* u (more info)
* a (see all)
* -l (technical info)

Meanings:

* PPID-parent process ID
* PID-process ID

ps ax |more to see all processes including daemons
pstree        Display the tree of running processes.
sa        Generates a summary of information about users’ processes that are stored in the /var/log/pacct file.
skill        Report process status.
snice        Report process status.
top        Display the processes that are using the most CPU resources.
CTRL-C        Kills the current job.
&         At the end of the command makes it run in the background.

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Linux File Structure

DATARECOVERYUNION.COM05 mins

linux file structureLinux file structure files are grouped according to purpose. Ex: commands, data files, documentation. Parts of a Unix directory tree are listed below. All directories are grouped under the root entry “/”.

root – The home directory for the root user
home – Contains the user’s home directories along with directories for services

  • ftp
  • HTTP
  • samba
  • george

bin – Commands needed during bootup that might be needed by normal users
sbin – Like bin but commands are not intended for normal users. Commands run by LINUX.
proc – This filesystem is not on a disk. It is a virtual filesystem that exists in the kernels imagination which is memory.

  • 1 – A directory with info about process number 1. Each process has a directory below proc.

usr – Contains all commands, libraries, man pages, games and static files for normal operation.

  • bin – Almost all user commands. some commands are in /bin or /usr/local/bin.
  • sbin – System admin commands not needed on the root filesystem. e.g., most server programs.
  • include – Header files for the C programming language. Should be below /user/lib for consistency.
  • lib – Unchanging data files for programs and subsystems
  • local – The place for locally installed software and other files.
  • man – Manual pages
  • info – Info documents
  • doc – Documentation
  • tmp
  • X11R6 – The X windows system files. There is a directory similar to usr below this directory.
  • X386 – Like X11R6 but for X11 release 5

boot – Files used by the bootstrap loader, LILO. Kernel images are often kept here.
lib – Shared libraries needed by the programs on the root filesystem

  • modules – Loadable kernel modules, especially those needed to boot the system after disasters.

dev – Device files
etc – Configuration files specific to the machine.

  • skel – When a home directory is created it is initialized with files from this directory
  • sysconfig – Files that configure the linux system for devices.

var – Contains files that change for mail, news, printers log files, man pages, temp files
file

  • lib – Files that change while the system is running normally
  • local – Variable data for programs installed in /usr/local.
  • lock – Lock files. Used by a program to indicate it is using a particular device or file
  • log – Log files from programs such as login and syslog which logs all logins and logouts.
  • run – Files that contain information about the system that is valid until the system is next booted
  • spool – Directories for mail, printer spools, news and other spooled work.
  • tmp – Temporary files that are large or need to exist for longer than they should in /tmp.
  • catman – A cache for man pages that are formatted on demand

mnt – Mount points for temporary mounts by the system administrator.
tmp – Temporary files. Programs running after bootup should use /var/tmp.

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