1a/b.

lab46:~$ ps
USER       PID %CPU %MEM    VSZ   RSS TTY      STAT START   TIME COMMAND
dblanch1 25797  2.3  0.1  13636  1976 pts/22   SNs  10:14   0:00 -bash
dblanch1 25839  0.0  0.0   8588   980 pts/22   RN+  10:15   0:00 ps u

1c. Use the t option to specify which tty to consider in it's output.

2a.

lab46:~$ ps axu 
USER       PID %CPU %MEM    VSZ   RSS TTY      STAT START   TIME COMMAND
root         1  0.0  0.0   8356   796 ?        Ss   Apr29   0:10 init [2]  
root         2  0.0  0.0      0     0 ?        S    Apr29   0:00 [kthreadd]
root         3  0.0  0.0      0     0 ?        S    Apr29   1:55 [migration/0]
root         4  0.0  0.0      0     0 ?        S    Apr29   0:02 [ksoftirqd/0]
root         5  0.0  0.0      0     0 ?        S    Apr29   0:00 [watchdog/0]
root         6  0.0  0.0      0     0 ?        S    Apr29   3:00 [migration/1]
root         7  0.0  0.0      0     0 ?        S    Apr29   0:04 [ksoftirqd/1]
root         8  0.0  0.0      0     0 ?        S    Apr29   0:00 [watchdog/1]
root         9  0.0  0.0      0     0 ?        S    Apr29   3:31 [events/0]
root        10  0.0  0.0      0     0 ?        S    Apr29   3:28 [events/1]
root        11  0.0  0.0      0     0 ?        S    Apr29   0:00 [cpuset]
root        12  0.0  0.0      0     0 ?        S    Apr29   0:00 [khelper]
root        13  0.0  0.0      0     0 ?        S    Apr29   0:00 [netns]
root        14  0.0  0.0      0     0 ?        S    Apr29   0:00 [async/mgr]
root        15  0.0  0.0      0     0 ?        S    Apr29   0:00 [pm]
root        16  0.0  0.0      0     0 ?        S    Apr29   0:00 [xenwatch]
root        17  0.0  0.0      0     0 ?        S    Apr29   0:00 [xenbus]
root        18  0.0  0.0      0     0 ?        S    Apr29   0:02 [sync_supers]
root        19  0.0  0.0      0     0 ?        S    Apr29   0:01 [bdi-default]
root        20  0.0  0.0      0     0 ?        S    Apr29   0:00 [kintegrityd/0]
root        21  0.0  0.0      0     0 ?        S    Apr29   0:00 [kintegrityd/1]
root        22  0.0  0.0      0     0 ?        S    Apr29   0:07 [kblockd/0]
root        23  0.0  0.0      0     0 ?        S    Apr29   0:00 [kblockd/1]
root        24  0.0  0.0      0     0 ?        S    Apr29   0:00 [kseriod]
root        27  0.0  0.0      0     0 ?        S    Apr29   0:00 [kondemand/0]
root        28  0.0  0.0      0     0 ?        S    Apr29   0:00 [kondemand/1]
root        29  0.0  0.0      0     0 ?        S    Apr29   0:00 [khungtaskd]
root        30  0.0  0.0      0     0 ?        S    Apr29   0:06 [kswapd0]
root        31  0.0  0.0      0     0 ?        SN   Apr29   0:00 [ksmd]
root        32  0.0  0.0      0     0 ?        S    Apr29   0:00 [aio/0]
root        33  0.0  0.0      0     0 ?        S    Apr29   0:00 [aio/1]
root        34  0.0  0.0      0     0 ?        S    Apr29   0:00 [crypto/0]
root        35  0.0  0.0      0     0 ?        S    Apr29   0:00 [crypto/1]
root        38  0.0  0.0      0     0 ?        S    Apr29   0:00 [khvcd]
root       113  0.0  0.0      0     0 ?        S    Apr29   0:59 [kjournald]
root       164  0.0  0.0  10416   696 ?        S<s  Apr29   0:00 udevd --daemon
root       204  0.0  0.0  10412   596 ?        S<   Apr29   0:00 udevd --daemon
root       205  0.0  0.0  10412   596 ?        S<   Apr29   0:00 udevd --daemon
mwitter3   335  0.0  0.1  62208  1856 ?        SNs  May03   0:00 SCREEN
mwitter3   336  0.0  0.1  13664  1972 pts/26   SNs  May03   0:00 /bin/bash
mwitter3   339  0.0  0.3  44304  5040 pts/26   SN+  May03   0:26 irssi
root       345  0.0  0.0      0     0 ?        S    Apr29   5:16 [rpciod/0]
root       346  0.0  0.0      0     0 ?        S    Apr29   1:21 [rpciod/1]
root       351  0.0  0.0      0     0 ?        S<   Apr29   0:00 [kslowd000]
root       352  0.0  0.0      0     0 ?        S<   Apr29   0:00 [kslowd001]
root       371  0.0  0.0      0     0 ?        S    Apr29   6:58 [nfsiod]
root       399  0.0  0.0      0     0 ?        S    Apr29   0:33 [kjournald]
root       499  0.0  0.0   6756  1032 ?        Ss   Apr29   0:00 dhclient -v -pf
daemon     554  0.0  0.0   8096   532 ?        Ss   Apr29   0:00 /sbin/portmap
root       767  0.0  0.0  43232   752 ?        S    Apr29   0:00 supervising sys
root       768  0.0  0.2  51344  4180 ?        Ss   Apr29   1:03 /usr/sbin/syslo
daemon     836  0.0  0.0  12400   492 ?        Ss   Apr29   0:00 /usr/sbin/atd
nobody     848  0.0  0.0   5988   612 ?        Ss   Apr29   0:01 /usr/bin/gdomap
root       854  0.0  0.1 167388  2448 ?        Ssl  Apr29   6:54 /usr/sbin/nscd
106        884  0.0  0.0  15276   728 ?        Ss   Apr29   0:00 /usr/bin/dbus-d
avahi      955  0.0  0.0  25904  1440 ?        S    Apr29   0:01 avahi-daemon: r
avahi      956  0.0  0.0  25772   492 ?        S    Apr29   0:00 avahi-daemon: c
mail       959  0.0  0.0  11736   628 ?        S    Apr29   0:00 /usr/sbin/nullm
root       971  0.0  0.0  14676   776 ?        Ss   Apr29   0:06 /usr/sbin/cron
nobody     979  0.0  0.3  49064  5280 ?        Sl   Apr29   0:59 python /usr/loc
root       999  0.0  0.0   8328   524 ?        Ss   Apr29   0:00 /usr/sbin/inetd
ntp       1006  0.0  0.1  32668  2120 ?        Rs   Apr29   0:25 /usr/sbin/ntpd
root      1013  0.0  0.0  43116  1108 ?        Ss   Apr29   0:02 /usr/sbin/sshd
statd     1046  0.0  0.0  14596   864 ?        Ss   Apr29   0:00 /sbin/rpc.statd
root      1055  0.0  0.1  59288  2188 ?        Ss   Apr29   0:33 /usr/sbin/rpc.i
root      1065  0.0  0.0      0     0 ?        S    Apr29   0:00 [nfsv4.0-svc]
root      1088  0.0  0.0   5932   628 hvc0     Ss+  Apr29   0:00 /sbin/getty 384
tedmist1  1558  0.0  0.1  62600  2316 ?        SNs  Apr29   0:02 SCREEN
tedmist1  1559  0.0  0.1  13668  1980 pts/5    SNs  Apr29   0:00 /bin/bash
tedmist1  1562  0.0  0.3  42768  5604 pts/5    SN+  Apr29   1:47 irssi
bh011695  2033  0.0  0.1  62216  1916 ?        SNs  Apr29   0:02 SCREEN irssi
bh011695  2034  0.0  0.3  42444  5280 pts/7    SNs+ Apr29   1:09 irssi
smeas     2433  0.0  0.1  62632  2400 ?        SNs  Apr29   0:03 SCREEN
smeas     2434  0.0  0.1  11572  1932 pts/6    SNs  Apr29   0:00 /bin/bash
smeas     2448  0.0  0.3  42504  5304 pts/6    RN+  Apr29   1:11 irssi
jpettie   2590  0.0  0.1  13664  2008 pts/23   SNs  May01   0:00 /bin/bash
jpettie   2593  0.0  0.3  42468  5264 pts/23   SN+  May01   1:30 irssi
jpettie   2603  0.0  0.1  13664  1984 pts/24   SNs  May01   0:00 /bin/bash
jpettie   2607  0.0  0.1  34696  2828 pts/24   SN+  May01   0:01 ssh positive@ir
jpettie   2983  0.0  0.2  64108  3740 ?        SNs  Apr29   1:01 SCREEN -l
jpettie   2984  0.0  0.1  13676  2048 pts/2    SNs+ Apr29   0:02 /bin/bash
mgardne8  4858  0.0  0.1  62396  2096 ?        SNs  May02   0:01 SCREEN
mgardne8  4859  0.0  0.1  13664  1976 pts/8    SNs  May02   0:00 /bin/bash
mgardne8  4863  0.0  0.3  42468  5224 pts/8    SN+  May02   0:50 irssi
eolson1   9999  0.0  0.1  62216  1940 ?        SNs  May04   0:00 SCREEN
eolson1  10000  0.0  0.1  13664  1972 pts/29   SNs  May04   0:00 /bin/bash
eolson1  10003  0.0  0.3  42432  5200 pts/29   SN+  May04   0:19 irssi
mgough   10016  0.0  0.7  56048 12216 ?        SN   Apr30   1:36 ./eggdrop irc.c
mgough   10019  0.0  0.7  55492 11548 ?        SN   Apr30   1:38 ./eggdrop webbo
mgough   10022  0.0  0.1  62216  1796 ?        SNs  Apr30   0:02 SCREEN
mgough   10023  0.0  0.1  13664  1976 pts/11   SNs  Apr30   0:00 /bin/bash
mgough   10027  0.0  0.3  42480  5324 pts/11   SN+  Apr30   1:03 irssi
alius    13293  0.0  0.1  62348  1976 ?        Ss   Apr30   0:03 SCREEN
alius    13294  0.0  0.1  13644  1948 pts/15   Ss   Apr30   0:00 /bin/bash
alius    13302  0.0  0.4  50204  7032 pts/15   S+   Apr30   1:01 irssi -c irc
jserosky 13411  0.0  0.1  62380  2060 ?        SNs  Apr30   0:03 SCREEN
jserosky 13412  0.0  0.1  13672  1984 pts/3    SNs  Apr30   0:00 /bin/bash
jserosky 13415  0.0  0.3  42456  5252 pts/3    SN+  Apr30   1:04 irssi
jhammo13 13661  0.0  0.1  62348  1968 ?        SNs  May05   0:00 SCREEN
jhammo13 13662  0.0  0.1  13664  1976 pts/30   SNs+ May05   0:00 /bin/bash
jhammo13 13666  0.0  0.1  13664  1972 pts/31   SNs  May05   0:00 /bin/bash
jhammo13 13669  0.0  0.3  42340  5184 pts/31   SN+  May05   0:07 irssi
jcavalu3 14468  0.0  0.1  62868  2560 ?        SNs  Apr30   0:02 SCREEN
jcavalu3 14469  0.0  0.1  13664  1984 pts/10   SNs  Apr30   0:00 /bin/bash
jcavalu3 14472  0.0  0.3  42472  5244 pts/10   SN+  Apr30   1:01 irssi
ddenunz2 14732  0.0  0.1  62348  2048 ?        SNs  May02   0:00 SCREEN
ddenunz2 14733  0.0  0.1  13656  1968 pts/13   SNs+ May02   0:00 /bin/bash
ddenunz2 14738  0.0  0.1  13656  1976 pts/16   SNs+ May02   0:00 /bin/bash
jjohns43 15578  0.0  0.1  62216  1796 ?        SNs  May05   0:00 SCREEN
jjohns43 15579  0.0  0.1  13668  1976 pts/25   SNs  May05   0:00 /bin/bash
jjohns43 15582  0.0  0.3  42344  5184 pts/25   SN+  May05   0:07 irssi
root     16150  0.0  0.2  89100  3984 ?        SNs  May02   0:00 sshd: asowers [
asowers  16152  0.0  0.1  89248  2040 ?        SN   May02   0:03 sshd: asowers@p
asowers  16153  0.0  0.1  13640  2000 pts/14   SNs+ May02   0:00 -bash
thakes3  16852  0.0  0.1  62216  1920 ?        SNs  May05   0:00 SCREEN
thakes3  16853  0.0  0.1  31528  2772 pts/27   SNs  May05   0:00 /bin/zsh
thakes3  16864  0.0  0.3  42444  5244 pts/27   SN+  May05   0:14 irssi
root     18334  0.0  0.2  89100  3984 ?        SNs  May05   0:00 sshd: mhuff3 [p
mhuff3   18336  0.0  0.1  89248  2160 ?        SN   May05   0:03 sshd: mhuff3@pt
mhuff3   18337  0.0  0.1  13640  2000 pts/28   SNs  May05   0:00 -bash
mhuff3   18859  0.0  0.2  13056  3812 pts/28   SN+  May05   0:00 nano hexed.c
root     21259  0.0  0.0      0     0 ?        S    03:05   0:00 [flush-0:17]
asowers  21734  0.0  0.1  62216  1792 ?        SNs  May03   0:01 SCREEN
asowers  21735  0.0  0.1  13672  1980 pts/9    SNs  May03   0:00 /bin/bash
asowers  21738  0.0  0.3  42432  5208 pts/9    SN+  May03   0:37 irssi
root     22920  0.0  0.0      0     0 ?        S    06:08   0:00 [flush-202:1]
mhuff3   25044  0.0  0.1  62348  2000 ?        SNs  May01   0:00 SCREEN
mhuff3   25045  0.0  0.1  13676  2004 pts/17   SNs+ May01   0:00 /bin/bash
mhuff3   25076  0.0  0.1  13668  1980 pts/18   SNs  May01   0:00 /bin/bash
mhuff3   25079  0.0  0.3  44304  5044 pts/18   SN+  May01   0:43 irssi
mhuff3   25081  0.0  0.1  62216  1812 ?        SNs  May01   0:01 SCREEN irssi
mhuff3   25082  0.0  0.3  42428  5284 pts/19   SNs+ May01   0:56 irssi
root     25126  0.0  0.2  89100  3972 ?        SNs  09:31   0:00 sshd: ahughe12 
ahughe12 25129  0.0  0.1  89100  2024 ?        SN   09:31   0:01 sshd: ahughe12@
ahughe12 25130  0.0  0.1  13644  2008 pts/21   SNs+ 09:31   0:00 -bash
ahughe12 25193  0.0  0.0  96168   720 pts/21   TN   09:33   0:00 ./a.out
root     25618  0.0  0.0      0     0 ?        S    09:56   0:00 [flush-202:2]
root     25624  0.0  0.2  89100  3988 ?        SNs  10:00   0:00 sshd: jpettie [
jpettie  25645  0.1  0.1  89100  2028 ?        SN   10:00   0:01 sshd: jpettie@p
jpettie  25646  0.0  0.1  13624  1960 pts/1    SNs  10:00   0:00 -bash
jpettie  25649  0.0  0.1  61848  2364 pts/1    SN+  10:00   0:00 screen -x
jpettie  25650  0.0  0.1  13668  2012 pts/4    SNs+ 10:00   0:00 /bin/bash
root     25781  0.0  0.2  89100  3984 ?        SNs  10:14   0:00 sshd: dblanch1 
dblanch1 25796  0.0  0.1  89248  2044 ?        RN   10:14   0:00 sshd: dblanch1@
dblanch1 25797  0.0  0.1  13644  2000 pts/22   SNs  10:14   0:00 -bash
root     25857  0.0  0.2  89100  3988 ?        SNs  10:15   0:00 sshd: dblanch1 
dblanch1 25859  0.0  0.1  89100  2028 ?        SN   10:15   0:00 sshd: dblanch1@
dblanch1 25860  0.0  0.1  13636  1972 pts/32   SNs  10:15   0:00 -bash
dblanch1 25863  0.0  0.1  10916  1668 pts/32   SN+  10:15   0:00 man ps
dblanch1 25873  0.0  0.0  10360  1000 pts/32   SN+  10:15   0:00 pager -s
dblanch1 26024  0.0  0.0   8588   980 pts/22   RN+  10:26   0:00 ps u axu
cbenne17 26300  0.0  0.1  62216  1812 ?        SNs  May01   0:01 SCREEN
cbenne17 26301  0.0  0.1  13680  1992 pts/20   SNs  May01   0:00 /bin/bash
cbenne17 26304  0.0  0.3  42344  5188 pts/20   SN+  May01   0:55 irssi
root     31734  0.0  0.2  89100  3988 ?        Ss   May01   0:00 sshd: alius [pr
alius    31736  0.0  0.1  89100  2032 ?        S    May01   0:17 sshd: alius@pts
alius    31737  0.0  0.1  13636  1964 pts/0    Ss   May01   0:00 -bash
alius    31745  0.0  0.1  61848  2364 pts/0    S+   May01   0:01 screen -r

2b. inetd's PID is 999

lab46:~$ ps ax | grep inetd
root       999  0.0  0.0   8328   524 ?        Ss   Apr29   0:00 /usr/sbin/inetd
dblanch1 25950  0.0  0.0  10092   864 pts/22   RN+  10:20   0:00 grep inetd

2c. The most active processes appear to me to be ones user's are currently running in the foreground.

3a.

file count.c
count.c: ASCII C program text

3c. It works. run as:

lab46:~$ ./count

3d. I need to add the executable's directory (my home directory) to my shell's $PATH variable.

lab46:~$ PATH="/usr/local/bin:/usr/bin:/bin:/usr/bin/X11:/usr/games:/usr/local/java/bin:/home/dblanch1

4a.

lab46:~$ time ./count > output

real    0m33.896s
user    0m33.582s
sys     0m0.184s

lab46:~$ cat output
The number is: 33554432.000000

4b. The output is the same, however rather than waiting at the terminal for count to end, it went to the background. CPU utilisation is at 100%.

5a. lab46:~$ (sleep 8; ls /var > multitask.lab.txt)& We want the whole procedure to be in the background, so we group it in parantheses, lest we put just the ls process in the background.

6. The shell does not let you logout because there are stopped jobs and jobs in the background, and the shell preventing the user from logging out is to ensure the user did not accidentally press ctrl+d and abruptly end currently running processes.

7a. Job 2. 7b. This worked, and resuspended with ctrl+z. 7c. links is still in the jobs list. 7d. fg 1 7e. ctrl+d 7f. cat is no longer in the jobs list. 7g. pressed enter and then q to exit. 7h. jobs list is empty.

8a. 1 8b. 15 8c. 9 8d. 2

9a.

lab46:~$ who
NAME       LINE         TIME             IDLE          PID COMMENT
tedmist1 + pts/1        2013-05-06 13:05 00:12       29024 (143.66.50.10)
smeas    + pts/6        2013-04-29 20:05 00:28        2434 (li583-226:S.0)
asowers  + pts/12       2013-05-06 13:00 00:31       28983 (172.16.198.165)
asowers  + pts/14       2013-05-02 22:57  old        16150 (cpe-69-205-233-207.stny.res.rr.com)
alius    + pts/15       2013-04-30 15:57 02:26       13294 (cpe-74-65-109-183:S.0)
ahughe12 + pts/21       2013-05-06 11:06 00:01       26550 (pod01.offbyone.lan)
dblanch1 + pts/22       2013-05-06 13:39 00:01       29409 (cpe-67-252-70-71.stny.res.rr.com)
mhuff3   + pts/28       2013-05-05 21:45 15:30       18334 (cpe-69-205-239-38.stny.res.rr.com)
wedge    - pts/32       2013-05-06 12:08 01:28       27853 (pod01.offbyone.lan)
bkrishe3 + pts/33       2013-05-06 12:30 00:13       28322 (10.80.3.183)
mwitter3 + pts/34       2013-05-06 13:25 00:12       29248 (cpe-69-205-163-56.stny.res.rr.com)
dblanch1 + pts/35       2013-05-06 13:47   .         29472 (cpe-67-252-70-71.stny.res.rr.com)
jserosky + pts/38       2013-05-06 13:29   .         29283 (pod00.offbyone.lan)

9b. 22 & 35 9c. 29412 & 29475, relatively

lab46:~$ ps xt
...
dblanch1 29412  0.0  0.1  13644  2000 pts/22   SNs  13:39   0:00 -bash
...
dblanch1 29475  0.1  0.1  13644  1976 pts/35   SNs  13:47   0:00 -bash
...

10a. Killing /dev/pts/22 10b.

lab46:~$ kill -9 29412

10c. “Connection to lab46.corning-cc.edu closed.” appeared on /dev/pts/22 10d. I am only logged in once now.

11a.

lab46:~$ ps -u statd
USER       PID %CPU %MEM    VSZ   RSS TTY      STAT START   TIME COMMAND
statd     1046  0.0  0.0  14596   840 ?        Ss   Apr29   0:00 /sbin/rpc.statd

11b. init's PID is 1, as it is the first process of executed by the system.

lab46:~$ ps ax | grep init
root         1  0.0  0.0   8356   788 ?        Ss   Apr29   0:10 init [2]  
dblanch1 29888  0.0  0.0  10092   868 pts/35   RN+  13:56   0:00 grep init

11c. cron's PID is 971 and is owned by root. cron is a task scheduler in the sense that you can schedule a command to be executed at a specific time, or have it reoccur every so often.

lab46:~$ ps ax | grep cron
root       971  0.0  0.0  14676   776 ?        Ss   Apr29   0:06 /usr/sbin/cron
dblanch1 29894  0.0  0.0  10092   868 pts/35   RN+  13:57   0:00 grep cron

1a. grep “coast” -c < pelopwar.txt b. 9 c. grep '\<coast\>' -c < pelopwar.txt d. 8 e. grep '\<Dorian\>$' < pelopwar.txt f. grep '^\<Again\>' < pelopwar.txt

2a/b. egrep '^(\<Athens\>|\<Athenians\>)' < pelopwar.txt 2c/d. egrep '(\<Corinth\>|\<Corinthians\>)$' < pelopwar.txt

3. This produces no results as there is no line or string the file matching this.

Compiling Things:

as -o helloASM helloASM.s; ld -o helloASM helloASM.o
gcc -o helloC helloC.c
g++ -o helloCPP helloCPP.cc

All three compiling methods worked fine for me. The current directory is not in $PATH, so just typing the name of the binary in question is insufficient; it must be prefixed with a path.

file: helloC.c: ASCII C program text helloCPP.cc: ASCI C++ program text helloASM.S: ASCII assembler program text

gcc -s yields an assembler source file conversion of helloC.c

hello.o is a 64-bit relocatable ELF file, a UNIX executable format. It is an object file, so it is machine code nearly ready for execution, it just needs to be placed in another executable (which is why it is relocatable; either a finished form consisting of it's own code linked with necessary support libraries, or turned into a shared object and linked into another process; which is not the current case). The output matches as we just did what gcc would automatically do for us.

helloC could be compiled this way:

make helloC

Code Efficiency: helloC is 6546 bytes helloCPP is 8369 bytes helloASM is 935 bytes helloJAVA is 426 bytes

The resulting Java file is smaller than the other files because it does not link any support code into the bytecode file, instead linking it at run time.

dd: What is different? uptime is executable, and howlong is not. The permissions are different, because a regular user used dd to make the copy. howlong is not executable because UNIX does not by default create executable files. The differences exist because the actual file data is copied but not associated filesystem metadata, such as permissions, time and date, and the file name. file's output for both files is the same because it analyses the files' contents to determine it's type. In order to execute, howlong needs to be made executable. The only difference between the two programmes' output is the amount of time displayed as they were executed at separate times.

Comparisons: Using diff -s (which reports when both files are the same) causes it to report their file data is, in fact, the same. MD5 hashes are useful in data integrity because they provide an easy, compact way to check the contents of a file for any difference using an algorithm. diff can be used for checking changes between two different versions of a document (say you deleted a line from a document that you now decide that you needed, and you want to retrieve it).

The Exercises: 3a/b/c: To create the zero filled file:

dd bs=8kB count=1 if=/dev/zero of=test.file

I verified this with bvi. 3d. This would append the string to test.file 3e/f. The string start at byte 8001, so we can skip the first 8000 bytes:

dd bs=1 skip=8000 if=test.file of=string

4a. According to bvi, the file is 8186 bytes long. 4b. zeros. 4c. Not constant.

Byte Ranges (hexadecimal) - Size (decimal)
1000 -> 13A5              - (933 bytes)
19A7 -> 19BE              - (23 bytes)
1BBF->1BF6                - (55 bytes)

4d/e: There are three such ranges. Segment 1: ELF 64-bit executable

dd bs=1 count=933 skip 4096 if=data.file of=segment1

Segment 2: ASCII text

dd bs=1 count=23 skip=6567 if=data.file of=segment2

Segment 4: gzip compressed data

dd bs=1 count=55 skip=7103 if=data.file of=segment3  

In accordance with “The magic number is 42” [I hope the Earth doesn't get blown away soon for an interstellar highway], count is changed to 97 for segment3 such that the secret word can be extracted: “The secret word is: Monkeysnake.” Whatever that means.

1a/b.

lab46: ~$ grep 'System'
gnats:x:41:41:Gnats Bug-Reporting System(admin):/var/lib/gnats:/bin/sh

2.

lab46: ~$ grep '^[b-d][aeiou]' /etc/passwd
daemon:x:1:1:daemon:/usr/sbin:/bin/sh
bin:x:2:2:bin:/bin:/bin/sh
backup:x:34:34:backup:/var/backups:/bin/sh

This search looks for lines starting b, c, or d and is immediately followed by a vowel. Pattern searching is more powerful than looking for just a string literal because you can search unknown strings so long as you have some idea of their structure.

3a.

lab46: ~$ grep '^[dwb]' /etc/passwd
daemon:x:1:1:daemon:/usr/sbin:/bin/sh
bin:x:2:2:bin:/bin:/bin/sh
www-data:x:33:33:www-data:/var/www:/bin/sh
backup:x:34:34:backup:/var/backups:/bin/sh

3b.

lab46: ~$ grep '^[aeiou]h$'
root:x:0:0:root:/root:/bin/bash

4a. %s/<centre>/<center>/g 4b. %s/<\/CENTRE>/<\/center>/g 4c. %s/<b>/<string>/g 4d. %s<\/b>/<\/strong>/g

5a. lab46: ~$ ls -l /usr/share/dict | grep words This points to /etc/dictionaries-common/words 5b. This file contains words the are on individual lines. 5c.

lab46: ~$ cat words | wc -l
98569 words in this file

For this next set of exercises, I copied the words file to my cwd, /home/dblacnh1 in this case.

6a. cat words | egrep '^.{5}$' | wc -l; 6685 matches
6b. cat words | grep '^[dwbDWB]' | wc -l; 14617
6c. cat words | egrep '^[dD].*[wW].*[bB]$' | wc -l; 1 match: dweeb
6d. cat words | egrep '&[aeiou].*[aeiou]$' | wc -l; 1731 matches
6e. cat words | grep '^[dD][aeiou][est]$' | wc -l; 10 matches
6f. cat words | grep '^[^dwbDWB]' | wc -l; 83951 matches
6g. cat words | egrep '^[^t][^h].+' | wc -l; 90669 matches
6h. cat words | grep '^..e$' | wc -l ; 72 matches
6i. cat words | grep '.*bob.*[^b]$' | wc -l ; 41 matches
6j. cat words | grep 'blue.*' | wc -l ; 37 matches
6k. cat words | grep '[^aeiouyAEIOUY]*' | wc -l ; 204 matches
This should be 203 as 'Ångström' contains two vowels.
6l. cat words | grep '[^aeiou].[abcd][aeiou]$' | wc -l; 762 matches

*To make script1.sh run, we need to make it executable:

chmod +x script1.sh

Code for age.sh:

#!/bin/bash
echo "In what year were you born? (YYYY) "
read birth_year
current_year=`/bin/date +%Y`
let current_age=$current_year-$birth_year
echo "Your current age is: "$current_age

Code for guess1.sh:

#!/bin/bash
pick=$(($RANDOM % 20))
echo "Please pick a number [1,20]: "
read guess
if [ "$guess" -eq "$pick" ]; then
echo "Congrats! You guessed correctly."
else 
echo "You have three guesses left. Guess again: "
read guess

if [ "$guess" -eq "$pick" ]; then
	echo "Congrats! You guessed correctly."
else
	echo "You have two guess left. Guess again: "
	read guess
	if [ "$guess" -eq "$pick" ]; then
		echo "Congrats! You guessed correctly."
	else
		echo "You have one guess left. Guess again: "
		read guess
		if [ "$guess" -eq "$pick" ]; then
			echo "It's about bloody time you guessed right..."
		else
			echo "You have failed. The correct answer is "$pick
		fi
  		fi
	fi
fi

4a. To make the loop put the count all on one line, each separated by a space, change:

echo "$i"

to

echo -n "$i"

4b. To change the stepping and direction, change:

for ((i=1;i<=10;i++)); do

to

for ((i=20;i>=2;i-=2)); do

Code for modified color.sh (now colour.sh):

#!/bin/bash
echo -n "First colour is: "
for colour in red orange yellow green blue indigo violet; do
    if [ "$colour" = "violet" ]; then
	    echo -n "The final colour is: "
	    echo $colour
    elif [ "$colour" != "violet" ]; then
	    echo "$colour"
	    if [ "$colour" != "indigo" ]; then
		    echo -n "The next colour is: "
	    fi
    fi
done

Code for script6.sh:

#!/bin/bash
for((i=1; i<=8; i++)); do
  echo "$i" >> "file"$i
done

echo "Pick a number [1,8]: "
read number

for ((i=8; i>0; i--)); do
	let j=$i+1
if [ "$i" -gt "$number" ]; then
	mv "file"$i "file"$j
elif [ "$i" -eq "$number" ]; then
	mv "file"$i "file"$j
	echo "$number" >> "file"$number
fi
done

echo "$number" >> "file"$number

Code for script7.sh:

#~/bin/bash
ag=0
hm=0
ns=0
tz=0
q_files=0

echo -n "Directory to process: "
read curr_dir
cd $curr_dir
echo "Processing: $curr_dir ..."

a="`find ./ -name "a*" -maxdepth 1 | wc -l`"
b="`find ./ -name "b*" -maxdepth 1 | wc -l`"
c="`find ./ -name "c*" -maxdepth 1 | wc -l`"
d="`find ./ -name "d*" -maxdepth 1 | wc -l`"
e="`find ./ -name "e*" -maxdepth 1 | wc -l`"
f="`find ./ -name "f*" -maxdepth 1 | wc -l`"
g="`find ./ -name "g*" -maxdepth 1 | wc -l`"
let ag=$a+$b+$c+$d+$e+$f+$g
let q_files+=$ag
if [ "$ag" -gt 60 ]; then
	let ag=60
fi

h="`find ./ -name "h*" -maxdepth 1 | wc -l`"
i="`find ./ -name "i*" -maxdepth 1 | wc -l`"
j="`find ./ -name "j*" -maxdepth 1 | wc -l`"
k="`find ./ -name "k*" -maxdepth 1 | wc -l`"
l="`find ./ -name "l*" -maxdepth 1 | wc -l`"
m="`find ./ -name "m*" -maxdepth 1 | wc -l`"
let hm=$h+$i+$j+$k+$l+$m
let q_files+=$hm
if [ "$hm" -gt 60 ]; then
	let hm=60
fi

n="`find ./ -name "n*" -maxdepth 1 | wc -l`"
o="`find ./ -name "o*" -maxdepth 1 | wc -l`"
p="`find ./ -name "p*" -maxdepth 1 | wc -l`"
q="`find ./ -name "q*" -maxdepth 1 | wc -l`"
r="`find ./ -name "r*" -maxdepth 1 | wc -l`"
s="`find ./ -name "s*" -maxdepth 1 | wc -l`"
let ns=$n+$o+$p+$q+$r+$s
let q_files+=$ns
if [ "$ns" -gt 60 ]; then
let ns=60
fi

t="`find ./ -name "t*" -maxdepth 1 | wc -l`"
u="`find ./ -name "u*" -maxdepth 1 | wc -l`"
v="`find ./ -name "v*" -maxdepth 1 | wc -l`"
w="`find ./ -name "w*" -maxdepth 1 | wc -l`"
x="`find ./ -name "x*" -maxdepth 1 | wc -l`"
y="`find ./ -name "y*" -maxdepth 1 | wc -l`"
z="`find ./ -name "z*" -maxdepth 1 | wc -l`"
let tz=$t+$u+$v+$w+$x+$y+$z
let q_files+=tz
if [ "$tz" -gt 60 ]; then
   let tz=60
fi

echo "Total files: $q_files"

echo -n "(a->g): "
for ((c=0;c<ag;c++)); do
  echo -n "*"
done
echo 

echo -n "(h->m): "
for ((c=0;c<hm;c++)); do
  echo -n "*"
done
echo

echo -n "(n->s): "
for ((c=0;c<ns;c++)); do
  echo -n "*"
done
echo

echo -n "(t->z): "
for ((c=0;c<tz;c++)); do
  echo -n "*"
done
echo

1a. Permissions are 701.

lab46:~$ ls -l /home/ | grep dblanch1

1b & 1c. I used the id command. My UID is 5813, and I belong to a couple groups so I have two GIDs: 5000 (lab46), and 1730 (unix). 1d & 1e. root is the sysadmin, whose UID is 0 and GID is 0. I determined this by using:

lab46:~$ id root

2a. Using umask, my current umask is 0022. 2b. Current permissions correlate with the umask, as the permissions for the new file are -rw-r–r–. 2c. Permissions of this new file is 666. They correlate. 2d. To make new files' permission 640 by default, I used 027.

3a.

777 -> 111 111 111
077 -> 000 111 111
AND -> 000 111 111

3b.

Assuming a directory
777 -> 111 111 111
777 -> 111 111 111
AND -> 111 111 111

3c.

Assuming a directory
777

-226

551

Assuming a file
666

-226

441

3d.

777
074
703

4a & 4b. Using the id command, I belong to:

lab46    (GID 5000)
unix     (GID 1730)
dblanch1 (5813)

5a & 5b. Directories

fall2010 permissions are 730 and unix is the group
root permissions are 750 and the group is root
unix permissions are 750 and the group is unix
users permissions are 750 and the group is lab46.

5c. I cannot view unix/ME.TOO . unix/README: The mountain ate the dog. users/groups.cs: Up Up Down Down Left Right Left Right B A

5d. I cannot get into root because I am not a member of group root, and I cannot view the contents of fall2010 because I do not have read permissions to this file.

My inclination is to find files with whereis, but it's limited to searching along $PATH, so we'll go with find this time. Among the directories listed with find that a limits.h file is, I shall use /usr/include/limits.h. I called it:

lab46:~$ find / -name limits.h 2>/dev/null

On Lab46, the following is true: char is a four bit type. Has 2^4 (256) possible values. Signed Range: [-128,127] Unsigned Range: [0,255] short int is a sixteen bit type. Has 2^16 (65536) possible values. Signed Range: [-32768,32767] Unsigned Range: [0,65535]. int is a thirty-two bit type. Has 2^32 possible values. Signed Range: [ (-(2^32)/2), ((2^32)/2 - 1)] Unsigned Range: [0, ((2^32) - 1). long long int is a sixty-four bit type. Has 2^64 possible values. Signed Range: [ (-(2^64)/2), ((2^64)/2 -1)] Unsigned Range: [0, ((2^64) - 1).

“Testing the Limits” To compile:

lab46:~/devel$ gcc dtypes.c -o dtypes

Value of unsigned int, after: 429467295 This value is seen in limits.h, defined as the UINT_MAX macro. Value of signed int, after: -1 This is expected. The value is within signed int's range. The result of the modified code makes sense because the value will “roll over” (sort of like the digit wheel on old alarm clocks that had a wheel of digits for the tens of hours, ones of hours, tens of minutes, and ones of minutes). Modified code:

#include <stdio.h>
#include <limits.h>

int main()
{
    unsigned int a, x;
    signed short int b, y;
 
    a = 0; // zero not letter "O"
    b = SHRT_MAX;
    x = a - 1;
    y = b + 1;
 
    printf("signed short int before: %hd \t after: %hd\n", b, y);
 
    return(0);
}

“Playing with long long int” The minimum value of signed long long int: -9223372036854775808 One use of this data type could be to display the size of the American deficit to the dollar, truncated, of course. Code (C++):

#include <iostream>
#include <limits.h>
using namespace std;

int main(){
  cout << "***Playing with long long int***" << endl;
  cout << "Unsigned:" << endl;
  cout << "Min: " << 0 << " Max: " << ULLONG_MAX << endl;
  cout << "Signed: " << endl;
  cout << "Min: " << LLONG_MIN << " Max: " << LLONG_MAX << endl;
  return 0;
}

Case Study 0x6 - Device Files Looking at /dev: Some files null (character) random (character) zero (character) loop0 (block) xvda1 (block) xvda2 (block)

Filesystems: /dev/xvda1 is mounted at / /dev/xvda2 is mounted at /tmp /dev/xvda3 is mounted as swap (determined by runnning the following:

cat /etc/fstab | grep swap

nfs:/home is mounted at /home nfs:/lib/mail is mounted at /var/mail udev is mounted at /dev There are two temporary file systems, one resides in memory (/dev/shm), and the other is mounted at /lib/init/rw

Software Devices: The two terminals I was using were /dev/pts/28 and /dev/pts/74. Permissions on for both terminals are crw–w—-. Write permissions for group are enabled for the UNIX messaging facilities to function (ie, mesg returns y).

Terminal Pointer: Both methods are the same because /dev/tty points to the current terminal.

Also: cat'ing to /dev/null dumps the output of cat. /dev/null is useful for ignoring command output and making technical jokes.

I did Case Study 5 - Web Pages today. My web page is all set up, including a quote from Camus and Hesse. It's just basic HTML, covering some primitive tags such as <br> to break off into a new line, <p> & </p> to demarcate paragraphs, and creating lists with <ol> & </ol> (ordered list) and <ul> & </ul> (unordered list) tags. The URL of my web page is http://lab46.corning-cc.edu/~dblanch1/index.html .

Case Study 4 - Messaging Utilities

I performed this on my local system using two accounts, user doug on tty2 and user root on tty3. I first ensured messaging was enabled on each account by calling:

doug@slackware: ~$ mesg y
root@slackware: ~# mesg y

I then had doug write root “Hello”

doug@slackware: ~$ write root
Hello
// pressed CTRL+D here to exit.

Here is what root would see:

root@slackware: ~#
Message from doug@slackware on tty2 at 20:42 ...
Hello
EOF
// root pressed return here to get his shell back

root@slackware: ~# write doug; mesg n
I am busy. Do not interrupt. mesg is n now.

doug@slackware: ~$
Message from root@slackware on tty3 at 20:43
I am busy. Do not interrupt. mesg is n now.
EOF
doug@slackware: ~$ write root
write: root has messages disabled
doug@slackware: ~$ mesg n

root@slackware: ~# mesg y; write doug; mesg n
I can still message you. I am the sysadmin. You cannot ignore me.

// doug sees this, attempts to start a talk session, then realises his system has no talk daemon configured.

Some points about ytalk from the man pages, as I did not have time to actually configure a daemon and play with it: To bring up a shell while in a talk session, press ESC then S To invite another user to a session, press ESC then A To kick another user from a session, press ESC then D

Lab 4 - Basic Unix Shell Stuff Personalised my .signature file.

printenv brings this valuable information:

Shell: bash
Term: xterm
Path: /bin
      /usr/bin
      /usr/local/bin
      /usr/bin/X11
      /usr/games
      /usr/local/java/bin
      

In order to display what is in the PATH shell variable:

doug@slackware: ~$ echo $PATH

Current alias for ls:

alias ls='ls --color-auto'

Which, according to the man page, this colourises the ouptput of ls (shocking, I know) based on the file type. Some examples of these colours: plain text is white, directories are blue, archives are red, symlinks are cyan, and executable files are green. Important to note is the colourisation of the file types can be customised with another shell variable, LS_COLORS

Removing the alias for ls removes colourised output for ls when ls is called with no parameters because the shell no long supplies the colour paramter.

Recreating and customising the ls alias

alias ls='ls --colour=auto -k -s --block-size=K'

Changes made here: Calling ls in the shell now displays the total file size of the directory now, and the size of each individual file in front of the filename now, in KiB, and the output is colourised again.

History:

doug@slackware: ~$ history -c
//clears history
doug@slackware: ~$ echo "###"
###
dou@slackware: ~$ echo "You got it"
You got it
doug@slackware: ~$ echo "---"
---
doug@slackware: ~$ history
31 echo "###"
32 echo "You got it"
33 echo "---"
34 history
// 32 is the line number for "You got it"
doug@slackware !32
echo "You got it"
You got it

History cycling is useful if you mistype a command and need to correct (or at least this is my own personal, very common use for it).

Tab Completions: This is all fairly self explanatory. Skipping the first few parts of this to filling in vimtutor; to get a unique hit for tab completion to complete, at least vimt needs to be provided.

Not entirely sure when I originally posted this Lab 2 stuff, but I just noticed it was in the wrong section. So I am moving it.

Lab 2 Results:

10d. chmod 705 lab2

  //Needs executable permission because it is a directory
  

11c.

                                     /
                                     
                                     |
                                     
                   bin/ etc/ home/ lib/ sbin/ tmp/ usr/ var/
                             
                             |
                             
                          dblanch1/
                             
                             |
                             
                 making.waves unix.text some_assembly/
                 
                                            |
                                            
             a b c d e f g h u j k l m n o p q quest2 quest2.dblanch1.gz r s t u v w x y z

12. ls / | grep bin

  // Of note, I guess, neither /bin or /sbin are revealed to be symlinked to anything
  
  ls /usr | grep bin
  // Again, neither /usr/bin or /usr/sbin are symlinked to anything
  
  ls /usr/local/ | grep bin
  // Again, neither bin nor sbin here are symlinked to anything.
  
  // /bin and /sbin store binaries for the local system necessary for startup and single user mode
  // /usr/bin and /usr/sbin store binaries that are not necessary for startup or single user mode, and as such, can be shared on a server amongst many clients
  // /usr/local/bin and /usr/local/sbin store binaries that are specific to the local system, but do not need to be on other computers in the network
  // Obviously, the difference between bin and sbin is that bin holds user binaries, while sbin holds binaries useful to system administration
  
  

Worksheet for Week 6

File Permissions

755
321
421
663

File Types

Normal
Directory
Special file, character. Used for raw input/output to devices
Special file, block. Used for block input/output to devices. Often used with disk drives.

Modifying File Permissions Based on File Type

Do not modify. Normal file.
chmod 725
chmod 625
chmod 627

Absolute vs Relative

Absolute. The root directory is explicitly mentioned.
Relative. Up one directory level from the current working directory (.. is explicitly mentioned).
Relative. No root directory is specified, so the current working directory's path is used.
Absolute. Root directory is explicitly mentioned.

It might help if I posted how I overcame the challenge round…

rm ./?\ challenge\ round\ ?
rm: remove regular file `./- challenge round -'? y

The results of the exercise for Case Study 2

1a. Choosing files:

“'ls' * HI! *”

“??? can you delete me ???.abc”

“compres “this” file.data”

1b. cat ?ls*

    Will the weird filenames ever end?
    
    rm *can\ you*
    rm: remove regular file `??? can you delete me ???.abc'? y
      //verify
    ls | grep can
      //amazing... nothing appeared...
    
    gzip compress*
      //Compresses fine.
    ls | grep compress
    compress "this" file.data.gz

2a. Choosing files:

“* watch out! *”

“change my\ name.file”

“just a simple file.txt”

2b. cat \*\*\*\ watch\ out\!\ \*\*\*

  Care must be taken when using the '!' symbol, as it deals with history.

  mv change\ my\\\ name.file "change my name.file" && cat change*
  This file has spaces and a backslash in its name.
  
  cat just\ a\ simple\ file.txt
  Simple, but simpler without the spaces!
    

3a. Choosing files:

“#pico28903#”

“( paranthesis & other odd things)”

“one, 'two', three, “four””

3b. cat “#pico28903#”

  laLAA... pretend this is a pico temp file.

  cat "( paranthesis & other odd things)"
  Are we having fun yet?
  
  cat "one, 'two', three, "four""
  cat: one, 'two', three, four: No such file or directory
    //This is because the double quotes around 'four' need to be escaped
  cat "one, 'two', three, \"four\""
  spaces, commas, two types of quotes... oh my!

Completed the puzzle case study. Not really what I was expecting based on the name. Kind of disappointing, actually.

I have not had much time to work on my e-mail server project as of yet, so progress on that is where it was last week, unfortunately. This should change this week, though.

But anyway, I am starting to do the text processing lab. Here are my thoughts on it so far:

To get wc(1) to display just the line count of /etc/passwd, we would call:

lab46:~$ wc -l /etc/passwd

and this tells us there are twenty-seven lines in the file. Alternatively, we can use the long parameter format, according to its man page, and use –lines instead of -l

To display just the first sixteen lines of /etc/passwd, we would call:

lab46:~$ head -n 16 /etc/passwd

Alternatively, we can use the long parameter format and use –lines instead of -n.

To display just the last eight lines of /etc/passwd, we would call:

lab46:$ tail -n 8 /etc/passwd

Alternatively, we can use the long parameter format and use –lines instead of -n.

The -f (–follow) parameter is used to follow changes to a file. This would be especially useful for following changes to, say, a log file.

I started work on my first project yesterday, setting up an e-mail server. I ran into an issue yesterday that seems to be resolved now, however; my noip DUC was unable to associate itself with my noip account. To clarify, noip provides free dynamic DNS for users without a static IP address (most residential users, myself included). The Dynamic Update Client would not during configuration associate itself with the domain I chose in my noip account. More to come later.

Well, even though I've concluded I probably shouldn't be doing the problems that appear to be randomly placed in /var/public/unix , I'm still going ahead and doing them as I wait on confirmation for setting up an e-mail server (on my home computer) as a project for this class. “puzzle” is puzzling indeed… so far it appears to be just a collection of oddly named empty files. A few things that strike me about it at the moment is a file called “eieio.c”, and a few files seem to have the same group of letters in them, with one adding to the set… I also wonder if all the ??.c files are at all related…

Actually finished “Quest 2”. For some reason it didn't dawn on me that .gz without tar.gz needed to be extracted with gunzip… I suppose I'm a little too used to tar. I did notice that there is no submit directory under /var/public/unix though, so I could not submit my completed quest. That does have me thinking that perhaps I was not supposed to start doing the quests.

I was doing “Quest 2”, redirecting a programme's stdout (to produce file z) was fairly simple (admittedly after a search with Google), a la

sys:~$ FUNC 1>DEST

1 is stdout, 2 is stderr. It is important to note that this is a bash feature and will not work with zsh, csh, tcsh, et cetera.

I was perusing the public directory yesterday and found a directory called quests. I am not entirely certain what these are exactly, but I noticed the one entitled “some_assembly” seems to be a good exercise for using tar and basic file management (save for symlinking, ln -s src dest). I'll start doing these little “quests” though, particularly since they likely will go along well with the labs for this course. Oh, and when I was setting up screen, I used man screen to help me set it up. You tend to develop those habits when (basically) building your own Linux installation (I used Arch Linux before moving to Slackware; I switched away from it because it was too much work to maintain).

Morse code eh? C'est trés interessant… and I'll be perfectly honest, I did not know there was a reverse line command in UNIX.

I was just reading through the page for Lab 0. Nothing exciting going on there. Decided to leave some evidence that I did it by playing around with alpine a little bit, talking to myself mainly (or exclusively). I know root is watching.

I setup Mercurial, irssi, and screen as per the UNIX task page. Following the instructions it was pretty simple. Logging in via ssh was also a breeze (I've setup it up before to access my home computer remotely, and an FTP server (pure-ftp) to access the files easily and not pay money).