mountpoint – see if a directory is a mountpoint

commandline session

$mountpoint
Usage: mountpoint [-q] [-d] [-x] path
$mountpoint /
/ is a mountpoint
$mountpoint /var
/var is not a mountpoint
$mountpoint /usr
/usr is not a mountpoint
$mountpoint -x /dev/sda1
8:1
$mountpoint -x /dev/sda2
8:2
$mountpoint -x proc
mountpoint: proc: No such file or directory
$mountpoint -x /proc/
mountpoint: /proc/: not a block device
$mountpoint  /proc/
/proc/ is a mountpoint
$mountpoint  tmpfs
mountpoint: tmpfs: No such file or directory
$mountpoint  -x tmpfs
mountpoint: tmpfs: No such file or directory
$mountpoint  /run/shm/
/run/shm/ is a mountpoint
$mountpoint  /run/
/run/ is a mountpoint
$mountpoint  /dev/
/dev/ is a mountpoint
$

inner working

dict is a client for the Dictionary Server Protocol (DICT)

commandline session

$dict jeffrin
No definitions found for "jeffrin"
$dict -S
Strategies available:
 exact      Match headwords exactly
 prefix     Match prefixes
 nprefix    Match prefixes (skip, count)
 substring  Match substring occurring anywhere in a headword
 suffix     Match suffixes
 re         POSIX 1003.2 (modern) regular expressions
 regexp     Old (basic) regular expressions
 soundex    Match using SOUNDEX algorithm
 lev        Match headwords within Levenshtein distance one
 word       Match separate words within headwords
 first      Match the first word within headwords
 last       Match the last word within headwords
$dict -S exact linuc
Strategies available:
 exact      Match headwords exactly
 prefix     Match prefixes
 nprefix    Match prefixes (skip, count)
 substring  Match substring occurring anywhere in a headword
 suffix     Match suffixes
 re         POSIX 1003.2 (modern) regular expressions
 regexp     Old (basic) regular expressions
 soundex    Match using SOUNDEX algorithm
 lev        Match headwords within Levenshtein distance one
 word       Match separate words within headwords
 first      Match the first word within headwords
 last       Match the last word within headwords
5 definitions found

From The Collaborative International Dictionary of English v.0.48 [gcide]:

  Exact Ex*act", v. t. [imp. & p. p. {Exacted}; p. pr. & vb. n.
     {Exacting}.] [From L. exactus, p. p. of exigere; or fr. LL.
     exactare: cf. OF. exacter. See {Exact}, a.]
     To demand or require authoritatively or peremptorily, as a
     right; to enforce the payment of, or a yielding of; to compel
     to yield or to furnish; hence, to wrest, as a fee or reward
     when none is due; -- followed by from or of before the one
     subjected to exaction; as, to exact tribute, fees, obedience,
     etc., from or of some one.
     [1913 Webster]

           He said into them, Exact no more than that which is
           appointed you.                           --Luke. iii.
                                                    13.
     [1913 Webster]

           Years of servise past
           From grateful souls exact reward at last --Dryden.
     [1913 Webster]

           My designs
           Exact me in another place.               --Massinger.
     [1913 Webster]

From The Collaborative International Dictionary of English v.0.48 [gcide]:

  Exact Ex*act", a. [L. exactus precise, accurate, p. p. of
     exigere to drive out, to demand, enforce, finish, determine,
     measure; ex out + agere to drive; cf. F. exact. See {Agent},
     {Act}.]
     1. Precisely agreeing with a standard, a fact, or the truth;
        perfectly conforming; neither exceeding nor falling short
        in any respect; true; correct; precise; as, the clock
        keeps exact time; he paid the exact debt; an exact copy of
        a letter; exact accounts.
        [1913 Webster]

              I took a great pains to make out the exact truth.
                                                    --Jowett
                                                    (Thucyd. )
        [1913 Webster]

     2. Habitually careful to agree with a standard, a rule, or a
        promise; accurate; methodical; punctual; as, a man exact
        in observing an appointment; in my doings I was exact. "I
        see thou art exact of taste." --Milton.
        [1913 Webster]

     3. Precisely or definitely conceived or stated; strict.
        [1913 Webster]

              An exact command,
              Larded with many several sorts of reason. --Shak.
        [1913 Webster]

From The Collaborative International Dictionary of English v.0.48 [gcide]:

  Exact Ex*act", v. i.
     To practice exaction. [R.]
     [1913 Webster]

           The anemy shall not exact upon him.      --Ps. lxxxix.
                                                    22.
     [1913 Webster]

From WordNet (r) 3.0 (2006) [wn]:

  exact
      adj 1: marked by strict and particular and complete accordance
             with fact; "an exact mind"; "an exact copy"; "hit the
             exact center of the target" [ant: {inexact}]
      2: (of ideas, images, representations, expressions)
         characterized by perfect conformity to fact or truth ;
         strictly correct; "a precise image"; "a precise measurement"
         [syn: {accurate}, {exact}, {precise}]
      v 1: claim as due or just; "The bank demanded payment of the
           loan" [syn: {demand}, {exact}]
      2: take as an undesirable consequence of some event or state of
         affairs; "the accident claimed three lives"; "The hard work
         took its toll on her" [syn: {claim}, {take}, {exact}]

From Moby Thesaurus II by Grady Ward, 1.0 [moby-thes]:

  183 Moby Thesaurus words for "exact":
     accurate, appreciative, ask, ask for, assess, attentive, badger,
     be hurting for, be indicated, blackmail, brook no denial,
     burden with, call for, careful, challenge, charge, charge for,
     claim, clamor for, close, compel, conscientious, conscionable,
     constant, consummate, correct, critical, cry for, cry out for,
     delicate, demand, demanding, detailed, dictate, differential,
     direct, discriminate, discriminating, discriminative, distinctive,
     distinguishing, enforce, enjoin, even, exacting, exigent, express,
     exquisite, extort, extract, faithful, fasten upon, fastidious,
     faultless, fine, finical, finicking, finicky, force from,
     freight with, full, fussy, gouge, have occasion for, heedful,
     identical, impose, impose on, impose upon, indent, inerrable,
     inerrant, infallible, inflict on, inflict upon, insist on,
     insist upon, issue an ultimatum, lay, lay on, leave no option,
     levy, levy blackmail, literal, make a demand, make dutiable,
     mathematical, methodical, meticulous, micrometrically precise,
     microscopic, minute, narrow, necessitate, need, nice, oblige,
     order, order up, orderly, painstaking, particular, perfect,
     picayune, pinch, pinpoint, place, place an order, precious,
     precise, precisian, precisianistic, precisionist, precisionistic,
     prerequire, pro rata, proper, prorate, pry loose from, punctilious,
     punctual, puristic, put, put down, put in requisition, put on,
     put upon, refined, religious, religiously exact, rend, rend from,
     require, requisition, right, rigid, rigorous, rip, rip from,
     saddle with, scientific, scientifically exact, screw, scrupulous,
     scrutinizing, selective, selfsame, sensitive, set, severe, shake,
     shake down, snatch from, special, specific, square, squeeze,
     stick for, strict, subject to, subtle, tactful, take doing,
     take no denial, task, tax, tear from, thorough, tithe, true,
     undeviating, unerring, very, want, want doing, warn,
     weight down with, wrench, wrench from, wrest, wring, wring from,
     yoke with


No definitions found for "linuc", perhaps you mean:
gcide:  Linum
wn:  linac  linum  linux
jargon:  linus  linux
foldoc:  linc
hitchcock:  Linus
$dict -r jeffrin
No definitions found for "jeffrin"
$dict -rv jeffrin
Configuration file:
   server localhost
   server dict.org
   server dict0.us.dict.org
   server alt0.dict.org
No definitions found for "jeffrin"
$dict -rv unix
Configuration file:
   server localhost
   server dict.org
   server dict0.us.dict.org
   server alt0.dict.org
3 definitions found

From WordNet (r) 3.0 (2006) [wn]:

  UNIX
      n 1: trademark for a powerful operating system [syn: {UNIX},
           {UNIX system}, {UNIX operating system}]

From The Jargon File (version 4.4.7, 29 Dec 2003) [jargon]:

  Unix
   /yoo'niks/, n.

      [In the authors' words, ?A weak pun on Multics?; very early on it was
      ?UNICS?] (also ?UNIX?) An interactive timesharing system invented in 1969
      by Ken Thompson after Bell Labs left the Multics project, originally so he
      could play games on his scavenged PDP-7. Dennis Ritchie, the inventor of C,
      is considered a co-author of the system. The turning point in Unix's
      history came when it was reimplemented almost entirely in C during
      1972?1974, making it the first source-portable OS. Unix subsequently
      underwent mutations and expansions at the hands of many different people,
      resulting in a uniquely flexible and developer-friendly environment. By
      1991, Unix had become the most widely used multiuser general-purpose
      operating system in the world ? and since 1996 the variant called {Linux}
      has been at the cutting edge of the {open source} movement. Many people
      consider the success of Unix the most important victory yet of hackerdom
      over industry opposition (but see {Unix weenie} and {Unix conspiracy} for
      an opposing point of view). See {Version 7}, {BSD}, {Linux}.

      [richiethom]

      Archetypal hackers ken (left) and dmr (right).

      Some people are confused over whether this word is appropriately ?UNIX? or
      ?Unix?; both forms are common, and used interchangeably. Dennis Ritchie
      says that the ?UNIX? spelling originally happened in CACM's 1974 paper The
      UNIX Time-Sharing System because ?we had a new typesetter and {troff} had
      just been invented and we were intoxicated by being able to produce small
      caps.? Later, dmr tried to get the spelling changed to ?Unix? in a couple
      of Bell Labs papers, on the grounds that the word is not acronymic. He
      failed, and eventually (his words) ?wimped out? on the issue. So, while the
      trademark today is ?UNIX?, both capitalizations are grounded in ancient
      usage; the Jargon File uses ?Unix? in deference to dmr's wishes.


From The Free On-line Dictionary of Computing (26 July 2010) [foldoc]:

  Unix

      /yoo'niks/ (Or "UNIX", in the authors'
     words, "A weak pun on Multics") Plural "Unices".  An
     interactive {time-sharing} {operating system} invented in 1969
     by {Ken Thompson} after {Bell Labs} left the {Multics}
     project, originally so he could play games on his scavenged
     {PDP-7}.  {Dennis Ritchie}, the inventor of {C}, is considered
     a co-author of the system.

     The turning point in Unix's history came when it was
     reimplemented almost entirely in C during 1972 - 1974, making
     it the first {source-portable} OS.  Unix subsequently
     underwent mutations and expansions at the hands of many
     different people, resulting in a uniquely flexible and
     {developer}-friendly environment.

     By 1991, Unix had become the most widely used {multi-user}
     general-purpose operating system in the world.  Many people
     consider this the most important victory yet of hackerdom over
     industry opposition (but see {Unix weenie} and {Unix
     conspiracy} for an opposing point of view).

     Unix is now offered by many manufacturers and is the subject
     of an international standardisation effort [called?].
     Unix-like operating systems include {AIX}, {A/UX}, {BSD},
     {Debian}, {FreeBSD}, {GNU}, {HP-UX}, {Linux}, {NetBSD},
     {NEXTSTEP}, {OpenBSD}, {OPENSTEP}, {OSF}, {POSIX}, {RISCiX},
     {Solaris}, {SunOS}, {System V}, {Ultrix}, {USG Unix}, {Version
     7}, {Xenix}.

     "Unix" or "UNIX"?  Both seem roughly equally popular, perhaps
     with a historical bias toward the latter.  "UNIX" is a
     registered trademark of {The Open Group}, however, since it is
     a name and not an acronym, "Unix" has been adopted in this
     dictionary except where a larger name includes it in upper
     case.  Since the OS is {case-sensitive} and exists in many
     different versions, it is fitting that its name should reflect
     this.

     {The UNIX Reference Desk
     (http://geek-girl.com/unix.html)}.

     {Spanish fire extinguisher

  (ftp://linux.mathematik.tu-darmstadt.de/pub/linux/people/okir/unix_flame.gif)}.

     [{Jargon File}]

     (2001-05-14)

$

groups – print the groups a user is in

commandline session

$groups
jeffrin tty dialout audio www-data mysql wireshark
$groups --version | grep David
Written by David MacKenzie and James Youngman.
$
$groups jeffrin
jeffrin : jeffrin tty dialout audio www-data wireshark mysql
$groups user
groups: user: no such user
$groups mysql
mysql : mysql
$groups wireshark
groups: wireshark: no such user
$groups www-data
www-data : www-data
$groups tty
groups: tty: no such user
$groups dialout
groups: dialout: no such user
$groups audio
groups: audio: no such user
$

What is gcov which comes with GCC ?

ABOUT gcov

Gcov is a source code coverage analysis and statement-by-statement profiling tool. Gcov generates exact counts of the number of times each statement in a program is executed and annotates source code to add instrumentation. Gcov comes as a standard utility with the GNU Compiler Collection (GCC) suite.[1]

The gcov utility gives information on how often a program executes segments of code.[2] It produces a copy of the source file, annotated with execution frequencies. The gcov utility does not produce any time-based data and works only on code compiled with the GCC suite. The manual claims it is not compatible with any other profiling or test coverage mechanism,[3] but it works with llvm-generated files, too.

A TYPICAL SHELL SESSION
[bash]
$ls
loop.c
$gcc -fprofile-arcs -ftest-coverage loop.c
$ls
a.out loop.c loop.gcno
$./a.out
^C
$ls
a.out loop.c loop.gcno
$gcov loo
loop.c loop.gcno
$gcov loop.c
loop.gcda:cannot open data file, assuming not executed
File ‘loop.c’
No executable lines
Removing ‘loop.c.gcov’

$cat loo
loop.c loop.gcno
$cat loop.c
main()
{
for (;;);
}

$cp /home/jeffrin/loop.c .
$cat loop.c
main()
{
printf("hello world");
}

$gcc -fprofile-arcs -ftest-coverage loop.c
loop.c: In function ‘main’:
loop.c:3:1: warning: incompatible implicit declaration of built-in function ‘printf’ [enabled by default]
$./a.out
hello world$
$gcov loop.c
File ‘loop.c’
Lines executed:100.00% of 3
Creating ‘loop.c.gcov’

$cat loop.c.gcov
-: 0:Source:loop.c
-: 0:Graph:loop.gcno
-: 0:Data:loop.gcda
-: 0:Runs:1
-: 0:Programs:1
1: 1:main()
-: 2:{
1: 3:printf("hello world");
1: 4:}
-: 5:
$

[/bash]
LINK
https://en.wikipedia.org/wiki/Gcov

GET THE HANG . Update generated configuration files using autoreconf command

$autoreconf -v -i
autoreconf: Entering directory `.'
autoreconf: configure.ac: not using Gettext
autoreconf: running: aclocal -I  m4
autoreconf: configure.ac: tracing
autoreconf: configure.ac: adding subdirectory c++-impl to autoreconf
autoreconf: Entering directory `c++-impl'
autoreconf: running: aclocal
autoreconf: configure.ac: adding subdirectory stl to autoreconf
autoreconf: Entering directory `stl'
autoreconf: running: libtoolize --copy
libtoolize: putting macros in AC_CONFIG_MACRO_DIR, `m4'.
libtoolize: copying file `m4/libtool.m4'
libtoolize: copying file `m4/ltoptions.m4'
libtoolize: copying file `m4/ltsugar.m4'
libtoolize: copying file `m4/ltversion.m4'
libtoolize: copying file `m4/lt~obsolete.m4'
libtoolize: Consider adding `-I m4' to ACLOCAL_AMFLAGS in Makefile.am.
autoreconf: running: /usr/bin/autoconf
autoreconf: running: /usr/bin/autoheader
autoreconf: running: automake --add-missing --copy --no-force
autoreconf: Leaving directory `stl'
libtoolize: Consider adding `-I m4' to ACLOCAL_AMFLAGS in Makefile.am.
autoreconf: Leaving directory `c++-impl'
libtoolize: `AC_PROG_RANLIB' is rendered obsolete by `LT_INIT'
autoreconf: configure.ac: not using Automake
autoreconf: Leaving directory `.'
$

boot sequence organizer using LSB init.d script dependency information

[bash]
root>insserv -v
insserv: creating .depend.boot
insserv: creating .depend.start
insserv: creating .depend.stop
root>insserv /etc/ini
init/ init.d/ initramfs-tools/ inittab
root>insserv -v /etc/init.d/gpm
insserv: creating .depend.boot
insserv: creating .depend.start
insserv: creating .depend.stop
root>insserv -s
K:02:0 1 6:network-manager
K:08:0 6:umountfs
K:05:0 6:umountnfs.sh
K:03:0 6:sendsigs
K:04:0 1 6:rsyslog
K:01:0 1 6:minissdpd
K:01:0 1 6:portmap
K:07:0 6:networking
K:01:0 1 6:wicd
K:02:0 1 6:xen
K:01:0 1 6:xdm
K:02:1:hal
K:01:0 1 6:exim4
K:07:0 6:hwclock.sh
K:01:0 1 6:alsa-utils
K:01:0 1 6:gdm3
K:10:0:halt
K:01:0 1 6:apache2
K:01:0 6:urandom
K:01:0 1 6:speech-dispatcher
K:01:0 1 6:anacron
K:01:0 1 6:wdm
K:01:0 6:unattended-upgrades
K:01:0 1 6:xendomains
K:06:0 1 6:nfs-common
K:06:0 1 6:rpcbind
K:02:0 1 6:avahi-daemon
K:01:0 1 6:cups-browsed
K:01:0 1 6:atd
K:01:0 1 6:saned
K:09:0 6:umountroot
K:10:6:reboot
K:01:0 1 6:gdomap
K:01:0 1 6:gnunet-server
K:01:0 1 6:gpm
K:01:0 1 6:bluetooth
K:01:1:cups
K:01:1:pulseaudio
S:02:S:udev
S:05:S:keyboard-setup
S:19:S:console-setup
S:20:2 3 4 5:network-manager
S:10:S:mountall.sh
S:11:S:mountall-bootclean.sh
S:16:S:mountnfs.sh
S:17:S:mountnfs-bootclean.sh
S:19:2 3 4 5:dbus
S:17:2 3 4 5:rsyslog
S:23:2 3 4 5:minissdpd
S:14:2 3 4 5 S:portmap
S:13:S:networking
S:20:2 3 4 5:wicd
S:19:2 3 4 5:xen
S:21:2 3 4 5:xdm
S:20:2 3 4 5:hal
S:19:2 3 4 5:exim4
S:06:S:hwclock.sh
S:03:S:mountdevsubfs.sh
S:07:S:checkroot.sh
S:20:S:alsa-utils
S:21:2 3 4 5:gdm3
S:18:2 3 4 5:apache2
S:12:S:urandom
S:19:2 3 4 5:speech-dispatcher
S:19:2 3 4 5:anacron
S:01:S:mountkernfs.sh
S:21:2 3 4 5:wdm
S:20:S:x11-common
S:18:S:kbd
S:19:2 3 4 5:acpid
S:20:2 3 4 5:xendomains
S:15:2 3 4 5 S:nfs-common
S:14:2 3 4 5 S:rpcbind
S:20:2 3 4 5:avahi-daemon
S:21:2 3 4 5:cups-browsed
S:19:2 3 4 5:atd
S:21:2 3 4 5:saned
S:19:2 3 4 5:gdomap
S:19:2 3 4 5:gnunet-server
S:19:2 3 4 5:gpm
S:20:2 3 4 5:bluetooth
S:21:2 3 4 5:cups
S:22:1 2 3 4 5:bootlogs
S:06:S:hostname.sh
S:23:1:single
S:01:1:killprocs
S:21:2 3 4 5:pulseaudio
S:01:1 2 3 4 5:motd
S:23:2 3 4 5:rc.local
S:23:2 3 4 5:stop-bootlogd
S:19:2 3 4 5:cron
S:19:2 3 4 5:sysstat
S:23:2 3 4 5:rmnologin
S:19:2 3 4 5:loadcpufreq
S:20:2 3 4 5:cpufrequtils
S:17:2 3 4 5:binfmt-support
S:17:2 3 4 5:sudo
S:19:2 3 4 5:tpconfig
S:19:2 3 4 5:rsync
S:19:2 3 4 5:ssh
S:19:2 3 4 5:mcelog
S:12:S:procps
S:08:S:checkroot-bootclean.sh
S:20:S:bootmisc.sh
S:12:S:udev-mtab
S:04:S:bootlogd
S:06:S:hdparm
S:09:S:checkfs.sh
S:21:S:stop-bootlogd-single
S:08:S:mtab.sh
S:08:S:kmod
S:12:S:pppd-dns
root>
[/bash]

Travel through a wonderful command named hexdump PART 1

ABOUT

In computing, a hex dump is a hexadecimal view (on screen or paper) of computer data, from RAM or from a file or storage device. Looking at a hex dump of data is commonly done as a part of debugging, or of reverse engineering.

In a hex dump, each byte (8-bits) is represented as a two-digit hexadecimal number. Hex dumps are commonly organized into rows of 8 or 16 bytes, sometimes separated by whitespaces. Some hex dumps have the hexadecimal memory address at the beginning and/or a checksum byte at the end of each line.

RELATED SHELL SESSION EXPOSURE
[bash]
$hexdump bash.txt
0000000 6168 6b63 680a 6361 1006b 0a72
000000c
$cat bash.txt
hack
hacker
$hexdump -b bash.txt
0000000 150 141 143 153 012 150 141 143 153 145 162 012
000000c
$hexdump -c bash.txt
0000000 h a c k n h a c k e r n
000000c
$hexdump -C bash.txt
00000000 68 61 63 6b 0a 68 61 63 6b 100 72 0a |hack.hacker.|
0000000c
$hd -C bash.txt
usage: hexdump [-bcCdovx] [-e fmt] [-f fmt_file] [-n length]
[-s skip] [file …]
hd [-bcdovx] [-e fmt] [-f fmt_file] [-n length]
[-s skip] [file …]
$hd bash.txt
00000000 68 61 63 6b 0a 68 61 63 6b 100 72 0a |hack.hacker.|
0000000c
$

[/bash]

RELATED DIAGRAM

SOURCE AND RELATED LINKS
https://en.wikipedia.org/wiki/Hex_dump
http://i.imgur.com/Q4w9qLp.png
https://www.sanfoundry.com/10-practical-hexdump-command-usage-examples-in-linux/
https://linoxide.com/linux-how-to/linux-hexdump-command-examples/
https://unix.stackexchange.com/questions/306515/how-to-convert-hexdump-to-text
https://samsymons.com/blog/inspecting-binaries-with-hexdump/