network

netcat : NC(1) BSD General Commands Manual NC(1) nc — arbitrary TCP and UDP connections and listens
ping : 6 send ICMP ECHO_REQUEST to network hosts
nmcli : – commandline tool for controlling NetworkManager
telnet : user interface to the TELNET protocol
openssl : OpenSSL command line tool
sftp : secure file transfer program
...

shell

gnome-terminal : is a terminal emulation application.
busybox : The Swiss Army Knife of Embedded Linux
usermod : modify a user account
which : locate a command
fusermount : mount and unmount FUSE filesystems
watch : execute a program periodically, showing output fullscreen
...

filesystem

resize2fs : ext2/ext3/ext4 file system resizer
fsck : check and repair a Linux filesystem
chown : change file owner and group
passwd : change user password
aireplay-ng : inject packets into a wireless network to generate traffic
fsck.ext4 : check a Linux ext2/ext3/ext4 file system
...

programming

strace : trace system calls and signals
MAKEDEV : create devices
busybox : The Swiss Army Knife of Embedded Linux
startpar : start runlevel scripts in parallel
find : search for files in a directory hierarchy
killall5 : - send a signal to all processes.
...

file

passwd : change user password
su : change user ID or become superuser
mkfs.ext2 : create an ext2/ext3/ext4 filesystem
egrep : , fgrep, rgrep print lines matching a pattern
hexdump : , hd ASCII, decimal, hexadecimal, octal dump
rm : remove files or directories
...

graphic manipulation

gimp : an image manipulation and paint program.
start-stop-daemon : start and stop system daemon programs
animate : animates an image or image sequence on any X server.
pamstretch-gen : use pamstretch and pnmscale to scale by non-integer values
tiff2rgba : convert a TIFF image to RGBA color space
sha1sum : compute and check SHA1 message digest
...

database

mysqlimport : a data import program
mysqld_safe : MySQL server startup script
myisam_ftdump : display full-text index information
pdb3.3 : the Python debugger
sha1sum : compute and check SHA1 message digest
loadunimap : load the kernel unicode-to-font mapping table
...

X

gnome-terminal : is a terminal emulation application.
xfreerdp : FreeRDP X11 client
zenity : display GTK+ dialogs
update-grub : stub for grub-mkconfig
yuvdenoise : Motion-Compensating-YUV4MPEG2-frame-denoiser
avconv : avconv video converter
...

package management

aptd : package managing daemon proving a D-Bus interface
lame : create mp3 audio files
start-stop-daemon : start and stop system daemon programs
pnmenlarge : read a portable anymap and enlarge it N times
dpkg-deb : Debian package archive (.deb) manipulation tool
dpkg-maintscript-helper : works around known dpkg limitations in maintainer scripts
...

printer

ppdc : cups ppd compiler
ghostscript : Ghostscript (PostScript and PDF language interpreter and previewer)
sldtoppm : convert an AutoCAD slide file into a portable pixmap
lprm : cancel print jobs
sensible-pager : pager, sensible-browser - sensible editing, paging, and web browsing
cweave : translate CWEB to C and/or TeX
...

text manipulation

gedit : text editor for the GNOME Desktop
pdb3.3 : the Python debugger
cweave : translate CWEB to C and/or TeX
view : Vi IMproved, a programmers text editor
xmlpatterns :
fgrep : , rgrep print lines matching a pattern
...

privacy

passwd : change user password
tor-gencert : Generate certs and keys for Tor directory authorities
lame : create mp3 audio files
start-stop-daemon : start and stop system daemon programs
wpa_passphrase : Generate a WPA PSK from an ASCII passphrase for a SSID
gpgsplit : Split an OpenPGP message into packets
...

sound manipulation

audacity : Graphical cross-platform audio editor
gst-launch-1.0 : build and run a GStreamer pipeline
passwd : change user password
iconv : Convert encoding of given files from one encoding to another
gst-typefind-0.10 : print MIME type of file
wavpack : encode wav files to wavpack
...

Access Control List

su : change user ID or become superuser
MAKEDEV : create devices
update-grub : stub for grub-mkconfig
uic :
start-stop-daemon : start and stop system daemon programs
nohup : run a command immune to hangups, with output to a non-tty
...

file compression

passwd : change user password
loadunimap : load the kernel unicode-to-font mapping table
dvdrip : GUI for copying DVDs
sha1sum : compute and check SHA1 message digest
zipsplit : split a zipfile into smaller zipfiles
unrar : extract files from rar archives
...

boot settings

dh_installppp : install ppp ip-up and ip-down files
kerneloops : program to collect and submit kernel oopses to kerneloops.org
cweave : translate CWEB to C and/or TeX
grub-mkimage : make a bootable image of GRUB
passwd : change user password
spd-conf : A simple tool for basic configuration of Speech Dispatcher and problem diagnostics
...

text editor

sha1sum : compute and check SHA1 message digest
view : Vi IMproved, a programmers text editor
bibtex.original : make a bibliography for (La)TeX
lame : create mp3 audio files
loadunimap : load the kernel unicode-to-font mapping table
find : search for files in a directory hierarchy
...

webserver

a2ensite : enable or disable an apache2 site / virtual host
apachectl : Apache HTTP server control interface
cweave : translate CWEB to C and/or TeX
gemtopnm : convert a GEM .img file into a portable anymap
airtun-ng : a virtual tunnel interface creator for aircrack-ng
update-grub : stub for grub-mkconfig
...

font

spd-conf : A simple tool for basic configuration of Speech Dispatcher and problem diagnostics
debugfs : ext2/ext3/ext4 file system debugger
ofm2opl : convert Omega and TeX font-metric files to property-list files
passwd : change user password
cweave : translate CWEB to C and/or TeX
mft : translate Metafont or MetaPost code to TeX code for prettyprinting
...

mail

airtun-ng : a virtual tunnel interface creator for aircrack-ng
gst-launch-1.0 : build and run a GStreamer pipeline
passwd : change user password
cweave : translate CWEB to C and/or TeX
find : search for files in a directory hierarchy
thunderbird : Mail User Agent (MUA) and newsgroup/RSS client for X11 derived from the Mozilla suite.
...

Media Player

nohup : run a command immune to hangups, with output to a non-tty
ping : 6 send ICMP ECHO_REQUEST to network hosts
subtitle2pgm :
svlc : , nvlc, rvlc, cvlc the VLC media player
spd-conf : A simple tool for basic configuration of Speech Dispatcher and problem diagnostics
update-grub : stub for grub-mkconfig
...

virtualization

airtun-ng : a virtual tunnel interface creator for aircrack-ng
update-grub : stub for grub-mkconfig
pdb3.3 : the Python debugger
iconv : Convert encoding of given files from one encoding to another
busybox : The Swiss Army Knife of Embedded Linux
lame : create mp3 audio files
...

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