notes on COMP343 lab activities
Table of Contents
- 1. Lab1
- 1.1. linux command line series
- 1.1.1. EP.1 intro - prompt
- 1.1.2. EP.2 command
- 1.1.3. EP.3 directory
- 1.1.4. EP.4 change stuff
- 1.1.5. EP.5 file permissions
- 1.1.6. EP.6 edit file
- 1.1.7. EP.7 word count
- 1.1.8. EP.8 text batch manipulation
- 1.1.9. EP.9 streams
- 1.1.10. EP.10 sudo
- 1.1.11. EP.11 ssh
- 1.1.12. EP.12 find
- 1.1.13. EP.13 search plain text
- 1.1.14. EP.14 screen
- 1.1.15. EP.15 hashing
- 1.1.16. EP.16 combining command
- 1.1. linux command line series
- Backlinks
this should not be a zettel strictly, but I included it here for reference
1. Lab1
signing up to immersive labs, and look around. immersive labs would provide lab exercises in:
- linux command line (17 exercises)
- security
- penetration testing
1.1. linux command line series
1.1.1. EP.1 intro - prompt
[username]@[computerName]:[path][user]in user section$indicates regular user,#indicates root
1.1.2. EP.2 command
lsls -a -l=ls -alchain parameters (only in commands where it is possible)
1.1.3. EP.3 directory
pwdprint working directorycd.~,.,..-(last directory) change direcotyrcat [filename]concatenateman [command]see manual
1.1.4. EP.4 change stuff
mvmoving and renamemv stuff [dir]movemv stuff this/that/->this/that/stuffmv stuff [file]renamemv stuff this/that->this/that,thathave the same content asstuff
1.1.5. EP.5 file permissions
ls -algives:drwxr-xrw 1 linux linux 4096 Jun 1 11:23d- directory.-regular filerwxfirst - owner permission; second - group; third - everyone else
chmod 756 filenumber: binary to decimal. 7 = 11 1 = rwx. 5 = 101 = r-xchmod 756 -R .- SUID and SGID - always run as user/group.
-rwS......-...rwS... - sticky file, cannot be deleted
-........t
1.1.6. EP.6 edit file
nanovim,vim +25 fileopen file at line 25
1.1.7. EP.7 word count
wc [filename] # line word char # 145 3655 34567 wc -w file wc -l file wc -m file # charater
1.1.8. EP.8 text batch manipulation
tr original replacement < input.txt > output.txt tr [:lower:] [:upper:] < lowercase sed ‘s/pattern_to_find/pattern_to_replace/g’ filewitherror.txt
charactor set [:alnum:] All letters and digits (A–Z, a–z, 0–9) [:alpha:] All letters (A–Z, a–z) [:digit:] All digits (0–9) [:punct:] All punctuation characters [:chars:]
tr charactor mapping: [aeb] [AEB]
1.1.9. EP.9 streams
- stdin - the entire command you have inputed, after the first token:
“12345” in
echo 12345 - stdout
some-program 1> output-and-error.txt 2>&1 with redirection
>whoami echo 3 > file # file: 3 echo 4 >> file # file: 34 echo 3 1> output # print output of program echo 3 to the file output echo 4 2> error
1.1.10. EP.10 sudo
sudo -l # list all command you can do with sudo sudo -u Alice cat file # cat file as if you are Alice sudo -i # swticht oroot. exit to exit su # change user to root su bob # change user to bob
1.1.11. EP.11 ssh
ssh linux@10.10.10.10 # will prompt for password of linux ssh linux@10.10.10.10 -i /home/linux/myprivatekey # if you have secret key and the corresponding public key is on 10.10.10.10 scp linux@10.10.10.10:/home/linux/this ./this
1.1.12. EP.12 find
find dir -name filename find dir -name "filename*" # find partial match find dir -perm 700 # find file with permission 700 (rwx------) find dir -user alice # find every file owned by alice
1.1.13. EP.13 search plain text
grep word [filename] > [output-filename]. # word is a regexp: "iron*" sort -r [filename] > [output-filename]
1.1.14. EP.14 screen
screen - multiplexing tool for command line windows
screen -ls # what screens are running screen -r screen1 # connect to/resume screen1 screen -S screen1 # connect to a new screen, named screen1 CTRL+A CTRL+D # detach from screen CTRL+A K # kill screen
1.1.15. EP.15 hashing
SHA-1 produces a 160-bit hash value expressed as 40 characters. An empty file called ‘example’ would result in this hash: da39a3ee5e6b4b0d3255bfef95601890afd80709 SHA-256 produces a 256-bit hash value expressed as 64 characters. The same empty file called ‘example’ would result in this hash: e3b0c44298fc1c149afbf4c8996fb92427ae41e4649b934ca495991b7852b855 MD5 produces a 128-bit hash value expressed as 32 hexadecimal characters. The ‘example’ file would result in this hash: d41d8cd98f00b204e9800998ecf8427e
sha1sum filename sha256sum filename md5sum filename
1.1.16. EP.16 combining command
a && b # do b if a success a || b # do b if a failed a;b # do b after a anyway a | b # use output of a as input of b a & b # run a, send a to backgournd, run b