Git is a powerful tool of every developer, it makes life easier and saves time. Git simplifies work with version control, provides easy access to history of changes, it can remove fear of irreparable consequences that allow us to experiment with program, gives us opportunity to collaborate, share projects with other people and a lot more.
Course on Udacity had a great educational impact on me, a big pros that it showed different real situations and how they are handled with Git. Were studied main concepts like commits, staging area, remote repository, branches and GitHub collaboration principles. Important idea of committing is to understand not only how make a commit but why and how often.
📚 Udacity course complete 📚
Command line skills are useful to operate with file directories, every action performed using GUI can be accomplished by line of code in CLI, this allows us to work faster and be ready to situation when graphical interface don't even exist. Also understanding of CLI is crucial to work with Git. Main shell tools that I've learned are:
- directory navigating commands like: pwd, ls, cd, mkdir, mv;
- files operating commands: touch, sort, uniq, grep, sed;
- output/input redirection commands: cat, >, >>, <, |;
- and concept that gives us opportunity to code frequently used commands into handy scripts.
The Linux Survival tutorial introduced me a several new commands like:
- 'less' that is used for reading large file contents
- 'lpq' and 'lpqm' used to show and remove printer's queue
- symbolic link that shows symbolic path of file location and created with 'ln' command
- 'df' command that displays free disk space
- 'ps' command, used to examine running programs or processes
An article on Linux Command provided a couple useful features like Brace Expansion, Command Substitution and now I comprehend the power of chmod 777 😄
📚 CLI course and Linux Survival complete 📚
This two completed courses, in fact, it's just repetition of earlier covered material with useful additions and some new Git features. What was learned new:
- Flags, that used to alter how a program functions and/or what is displayed. For example -p, --stat, --oneline, --decorate, --graph, --all for git log. This flags helps us to get more info about commits and operate with it in more convenient way;
- git show, to access info about particular commit and how it can be reached by HEAD reference;
- git tag, to label commits;
- git commit --amend, useful command to "cancel" most recent commit, allows us to add some files to staging area or change the commit message;
- git reset --soft(resets commit) --mixed(resets commit+index) --hard(resets commit+index+working area);
- git shortlog provides more clear view on commits history;
- Was introduced upstream, that helps us keep up to date our forked repository with original one;
- And at the end was reviewed powerful git rebase, that provides us ability to change past commits, for example rename, squash, delete them and lot more.
📚 Git collaboration course complete 📚
What's going to happen if program reaches maximum limit of stack ?
Will occur segmentation error named stack overflow, it happens when the stack pointer exceeds the stack bound.
What's going to happen if program requests a big (more then 128KB) memory allocation on heap ?
In Linux, will be performed anonymous memory mapping instead of using heap memory.
What's the difference between Text and Data memory segments ?
Text memory segment is read-only and stores all of the program's code, whereas data segment holds data that may be both readable and writable and used for static variables contents.
Output of `proc` command
Heap - [560682537000-5606825d3000]
Memory Mapping Segment - [7f8d43135000-7f8d43137000]
Stack - [7fffa75d8000-7fffa75f9000]
560681596000-5606815cf000 r-xp 00000000 08:01 409093 /usr/lib/upower/upowerd
5606817cf000-5606817d2000 r--p 00039000 08:01 409093 /usr/lib/upower/upowerd
5606817d2000-5606817d3000 rw-p 0003c000 08:01 409093 /usr/lib/upower/upowerd
560682537000-5606825d3000 rw-p 00000000 00:00 0 [heap]
7f8d34000000-7f8d34021000 rw-p 00000000 00:00 0
7f8d34021000-7f8d38000000 ---p 00000000 00:00 0
7f8d38000000-7f8d38021000 rw-p 00000000 00:00 0
7f8d38021000-7f8d3c000000 ---p 00000000 00:00 0
7f8d3c000000-7f8d3c021000 rw-p 00000000 00:00 0
7f8d3c021000-7f8d40000000 ---p 00000000 00:00 0
7f8d40091000-7f8d40092000 ---p 00000000 00:00 0
7f8d40092000-7f8d40892000 rw-p 00000000 00:00 0
7f8d40892000-7f8d40893000 ---p 00000000 00:00 0
7f8d40893000-7f8d41093000 rw-p 00000000 00:00 0
7f8d41093000-7f8d41094000 ---p 00000000 00:00 0
7f8d41094000-7f8d41894000 rw-p 00000000 00:00 0
7f8d41894000-7f8d41895000 ---p 00000000 00:00 0
7f8d41895000-7f8d42095000 rw-p 00000000 00:00 0
7f8d42095000-7f8d43131000 r--p 00000000 08:01 404792 /usr/lib/locale/locale-archive
7f8d43131000-7f8d43135000 rw-p 00000000 00:00 0
7f8d43135000-7f8d43137000 r--p 00000000 08:01 1054422 /lib/x86_64-linux-gnu/libuuid.so.1.3.0
7f8d43137000-7f8d4313b000 r-xp 00002000 08:01 1054422 /lib/x86_64-linux-gnu/libuuid.so.1.3.0
7f8d4313b000-7f8d4313c000 r--p 00006000 08:01 1054422 /lib/x86_64-linux-gnu/libuuid.so.1.3.0
7f8d4313c000-7f8d4313d000 r--p 00006000 08:01 1054422 /lib/x86_64-linux-gnu/libuuid.so.1.3.0
7f8d4313d000-7f8d4313e000 rw-p 00007000 08:01 1054422 /lib/x86_64-linux-gnu/libuuid.so.1.3.0
7f8d4313e000-7f8d4315c000 r-xp 00000000 08:01 1054352 /lib/x86_64-linux-gnu/libgpg-error.so.0.24.3
7f8d4315c000-7f8d4335c000 ---p 0001e000 08:01 1054352 /lib/x86_64-linux-gnu/libgpg-error.so.0.24.3
7f8d4335c000-7f8d4335d000 r--p 0001e000 08:01 1054352 /lib/x86_64-linux-gnu/libgpg-error.so.0.24.3
7f8d4335d000-7f8d4335e000 rw-p 0001f000 08:01 1054352 /lib/x86_64-linux-gnu/libgpg-error.so.0.24.3
7f8d4335e000-7f8d433dd000 r-xp 00000000 08:01 409548 /usr/lib/x86_64-linux-gnu/libgmp.so.10.3.2
7f8d433dd000-7f8d435dd000 ---p 0007f000 08:01 409548 /usr/lib/x86_64-linux-gnu/libgmp.so.10.3.2
7f8d435dd000-7f8d435de000 r--p 0007f000 08:01 409548 /usr/lib/x86_64-linux-gnu/libgmp.so.10.3.2
7f8d435de000-7f8d435df000 rw-p 00080000 08:01 409548 /usr/lib/x86_64-linux-gnu/libgmp.so.10.3.2
7f8d435df000-7f8d43612000 r-xp 00000000 08:01 409604 /usr/lib/x86_64-linux-gnu/libhogweed.so.4.4
7f8d43612000-7f8d43811000 ---p 00033000 08:01 409604 /usr/lib/x86_64-linux-gnu/libhogweed.so.4.4
7f8d43811000-7f8d43812000 r--p 00032000 08:01 409604 /usr/lib/x86_64-linux-gnu/libhogweed.so.4.4
7f8d43812000-7f8d43813000 rw-p 00033000 08:01 409604 /usr/lib/x86_64-linux-gnu/libhogweed.so.4.4
7f8d43813000-7f8d43815000 rw-p 00000000 00:00 0
7f8d43815000-7f8d43849000 r-xp 00000000 08:01 409745 /usr/lib/x86_64-linux-gnu/libnettle.so.6.4
7f8d43849000-7f8d43a48000 ---p 00034000 08:01 409745 /usr/lib/x86_64-linux-gnu/libnettle.so.6.4
7f8d43a48000-7f8d43a4a000 r--p 00033000 08:01 409745 /usr/lib/x86_64-linux-gnu/libnettle.so.6.4
7f8d43a4a000-7f8d43a4b000 rw-p 00035000 08:01 409745 /usr/lib/x86_64-linux-gnu/libnettle.so.6.4
7f8d43a4b000-7f8d43a5b000 r--p 00000000 08:01 409939 /usr/lib/x86_64-linux-gnu/libunistring.so.2.1.0
7f8d43a5b000-7f8d43a8f000 r-xp 00010000 08:01 409939 /usr/lib/x86_64-linux-gnu/libunistring.so.2.1.0
7f8d43a8f000-7f8d43bc6000 r--p 00044000 08:01 409939 /usr/lib/x86_64-linux-gnu/libunistring.so.2.1.0
7f8d43bc6000-7f8d43bc7000 ---p 0017b000 08:01 409939 /usr/lib/x86_64-linux-gnu/libunistring.so.2.1.0
7f8d43bc7000-7f8d43bca000 r--p 0017b000 08:01 409939 /usr/lib/x86_64-linux-gnu/libunistring.so.2.1.0
7f8d43bca000-7f8d43bcb000 rw-p 0017e000 08:01 409939 /usr/lib/x86_64-linux-gnu/libunistring.so.2.1.0
7f8d43bcb000-7f8d43bcd000 r--p 00000000 08:01 409626 /usr/lib/x86_64-linux-gnu/libidn2.so.0.3.4
7f8d43bcd000-7f8d43bd1000 r-xp 00002000 08:01 409626 /usr/lib/x86_64-linux-gnu/libidn2.so.0.3.4
7f8d43bd1000-7f8d43be8000 r--p 00006000 08:01 409626 /usr/lib/x86_64-linux-gnu/libidn2.so.0.3.4
7f8d43be8000-7f8d43be9000 r--p 0001c000 08:01 409626 /usr/lib/x86_64-linux-gnu/libidn2.so.0.3.4
7f8d43be9000-7f8d43bea000 rw-p 0001d000 08:01 409626 /usr/lib/x86_64-linux-gnu/libidn2.so.0.3.4
7f8d43bea000-7f8d43c15000 r--p 00000000 08:01 409775 /usr/lib/x86_64-linux-gnu/libp11-kit.so.0.3.0
7f8d43c15000-7f8d43ca9000 r-xp 0002b000 08:01 409775 /usr/lib/x86_64-linux-gnu/libp11-kit.so.0.3.0
7f8d43ca9000-7f8d43d04000 r--p 000bf000 08:01 409775 /usr/lib/x86_64-linux-gnu/libp11-kit.so.0.3.0
7f8d43d04000-7f8d43d05000 ---p 0011a000 08:01 409775 /usr/lib/x86_64-linux-gnu/libp11-kit.so.0.3.0
7f8d43d05000-7f8d43d0f000 r--p 0011a000 08:01 409775 /usr/lib/x86_64-linux-gnu/libp11-kit.so.0.3.0
7f8d43d0f000-7f8d43d19000 rw-p 00124000 08:01 409775 /usr/lib/x86_64-linux-gnu/libp11-kit.so.0.3.0
7f8d43d19000-7f8d43d1b000 r--p 00000000 08:01 1054408 /lib/x86_64-linux-gnu/librt-2.28.so
7f8d43d1b000-7f8d43d1f000 r-xp 00002000 08:01 1054408 /lib/x86_64-linux-gnu/librt-2.28.so
7f8d43d1f000-7f8d43d21000 r--p 00006000 08:01 1054408 /lib/x86_64-linux-gnu/librt-2.28.so
7f8d43d21000-7f8d43d22000 r--p 00007000 08:01 1054408 /lib/x86_64-linux-gnu/librt-2.28.so
7f8d43d22000-7f8d43d23000 rw-p 00008000 08:01 1054408 /lib/x86_64-linux-gnu/librt-2.28.so
7f8d43d23000-7f8d43d2d000 r--p 00000000 08:01 1054330 /lib/x86_64-linux-gnu/libblkid.so.1.1.0
7f8d43d2d000-7f8d43d5e000 r-xp 0000a000 08:01 1054330 /lib/x86_64-linux-gnu/libblkid.so.1.1.0
7f8d43d5e000-7f8d43d6e000 r--p 0003b000 08:01 1054330 /lib/x86_64-linux-gnu/libblkid.so.1.1.0
7f8d43d6e000-7f8d43d72000 r--p 0004a000 08:01 1054330 /lib/x86_64-linux-gnu/libblkid.so.1.1.0
7f8d43d72000-7f8d43d73000 rw-p 0004e000 08:01 1054330 /lib/x86_64-linux-gnu/libblkid.so.1.1.0
7f8d43d73000-7f8d43d76000 rw-p 00000000 00:00 0
7f8d43d76000-7f8d43d77000 r--p 00000000 08:01 1054343 /lib/x86_64-linux-gnu/libdl-2.28.so
7f8d43d77000-7f8d43d79000 r-xp 00001000 08:01 1054343 /lib/x86_64-linux-gnu/libdl-2.28.so
7f8d43d79000-7f8d43d7a000 r--p 00003000 08:01 1054343 /lib/x86_64-linux-gnu/libdl-2.28.so
7f8d43d7a000-7f8d43d7b000 r--p 00003000 08:01 1054343 /lib/x86_64-linux-gnu/libdl-2.28.so
7f8d43d7b000-7f8d43d7c000 rw-p 00004000 08:01 1054343 /lib/x86_64-linux-gnu/libdl-2.28.so
7f8d43d7c000-7f8d43d83000 r-xp 00000000 08:01 409946 /usr/lib/x86_64-linux-gnu/libusbmuxd.so.4.0.0
7f8d43d83000-7f8d43f82000 ---p 00007000 08:01 409946 /usr/lib/x86_64-linux-gnu/libusbmuxd.so.4.0.0
7f8d43f82000-7f8d43f83000 r--p 00006000 08:01 409946 /usr/lib/x86_64-linux-gnu/libusbmuxd.so.4.0.0
7f8d43f83000-7f8d43f84000 rw-p 00007000 08:01 409946 /usr/lib/x86_64-linux-gnu/libusbmuxd.so.4.0.0
7f8d43f84000-7f8d44099000 r-xp 00000000 08:01 1054351 /lib/x86_64-linux-gnu/libgcrypt.so.20.2.3
7f8d44099000-7f8d44298000 ---p 00115000 08:01 1054351 /lib/x86_64-linux-gnu/libgcrypt.so.20.2.3
7f8d44298000-7f8d4429a000 r--p 00114000 08:01 1054351 /lib/x86_64-linux-gnu/libgcrypt.so.20.2.3
7f8d4429a000-7f8d4429f000 rw-p 00116000 08:01 1054351 /lib/x86_64-linux-gnu/libgcrypt.so.20.2.3
7f8d4429f000-7f8d442a0000 rw-p 00000000 00:00 0
7f8d442a0000-7f8d442b1000 r-xp 00000000 08:01 409917 /usr/lib/x86_64-linux-gnu/libtasn1.so.6.5.5
7f8d442b1000-7f8d444b1000 ---p 00011000 08:01 409917 /usr/lib/x86_64-linux-gnu/libtasn1.so.6.5.5
7f8d444b1000-7f8d444b2000 r--p 00011000 08:01 409917 /usr/lib/x86_64-linux-gnu/libtasn1.so.6.5.5
7f8d444b2000-7f8d444b3000 rw-p 00012000 08:01 409917 /usr/lib/x86_64-linux-gnu/libtasn1.so.6.5.5
7f8d444b3000-7f8d444df000 r--p 00000000 08:01 408310 /usr/lib/x86_64-linux-gnu/libgnutls.so.30.22.0
7f8d444df000-7f8d445da000 r-xp 0002c000 08:01 408310 /usr/lib/x86_64-linux-gnu/libgnutls.so.30.22.0
7f8d445da000-7f8d4463e000 r--p 00127000 08:01 408310 /usr/lib/x86_64-linux-gnu/libgnutls.so.30.22.0
7f8d4463e000-7f8d4464d000 r--p 0018a000 08:01 408310 /usr/lib/x86_64-linux-gnu/libgnutls.so.30.22.0
7f8d4464d000-7f8d4464e000 rw-p 00199000 08:01 408310 /usr/lib/x86_64-linux-gnu/libgnutls.so.30.22.0
7f8d4464e000-7f8d44651000 rw-p 00000000 00:00 0
7f8d44651000-7f8d44653000 r--p 00000000 08:01 1054398 /lib/x86_64-linux-gnu/libpcre.so.3.13.3
7f8d44653000-7f8d446a5000 r-xp 00002000 08:01 1054398 /lib/x86_64-linux-gnu/libpcre.so.3.13.3
7f8d446a5000-7f8d446c3000 r--p 00054000 08:01 1054398 /lib/x86_64-linux-gnu/libpcre.so.3.13.3
7f8d446c3000-7f8d446c4000 r--p 00071000 08:01 1054398 /lib/x86_64-linux-gnu/libpcre.so.3.13.3
7f8d446c4000-7f8d446c5000 rw-p 00072000 08:01 1054398 /lib/x86_64-linux-gnu/libpcre.so.3.13.3
7f8d446c5000-7f8d446cc000 r-xp 00000000 08:01 409483 /usr/lib/x86_64-linux-gnu/libffi.so.6.0.4
7f8d446cc000-7f8d448cb000 ---p 00007000 08:01 409483 /usr/lib/x86_64-linux-gnu/libffi.so.6.0.4
7f8d448cb000-7f8d448cc000 r--p 00006000 08:01 409483 /usr/lib/x86_64-linux-gnu/libffi.so.6.0.4
7f8d448cc000-7f8d448cd000 rw-p 00007000 08:01 409483 /usr/lib/x86_64-linux-gnu/libffi.so.6.0.4
7f8d448cd000-7f8d448d1000 r--p 00000000 08:01 1049289 /lib/x86_64-linux-gnu/libudev.so.1.6.11
7f8d448d1000-7f8d448e4000 r-xp 00004000 08:01 1049289 /lib/x86_64-linux-gnu/libudev.so.1.6.11
7f8d448e4000-7f8d448eb000 r--p 00017000 08:01 1049289 /lib/x86_64-linux-gnu/libudev.so.1.6.11
7f8d448eb000-7f8d448ec000 r--p 0001d000 08:01 1049289 /lib/x86_64-linux-gnu/libudev.so.1.6.11
7f8d448ec000-7f8d448ed000 rw-p 0001e000 08:01 1049289 /lib/x86_64-linux-gnu/libudev.so.1.6.11
7f8d448ed000-7f8d448f8000 r--p 00000000 08:01 1054368 /lib/x86_64-linux-gnu/libmount.so.1.1.0
7f8d448f8000-7f8d44930000 r-xp 0000b000 08:01 1054368 /lib/x86_64-linux-gnu/libmount.so.1.1.0
7f8d44930000-7f8d44942000 r--p 00043000 08:01 1054368 /lib/x86_64-linux-gnu/libmount.so.1.1.0
7f8d44942000-7f8d44944000 r--p 00054000 08:01 1054368 /lib/x86_64-linux-gnu/libmount.so.1.1.0
7f8d44944000-7f8d44945000 rw-p 00056000 08:01 1054368 /lib/x86_64-linux-gnu/libmount.so.1.1.0
7f8d44945000-7f8d44946000 rw-p 00000000 00:00 0
7f8d44946000-7f8d4494a000 r--p 00000000 08:01 1054407 /lib/x86_64-linux-gnu/libresolv-2.28.so
7f8d4494a000-7f8d44959000 r-xp 00004000 08:01 1054407 /lib/x86_64-linux-gnu/libresolv-2.28.so
7f8d44959000-7f8d4495d000 r--p 00013000 08:01 1054407 /lib/x86_64-linux-gnu/libresolv-2.28.so
7f8d4495d000-7f8d4495e000 r--p 00016000 08:01 1054407 /lib/x86_64-linux-gnu/libresolv-2.28.so
7f8d4495e000-7f8d4495f000 rw-p 00017000 08:01 1054407 /lib/x86_64-linux-gnu/libresolv-2.28.so
7f8d4495f000-7f8d44961000 rw-p 00000000 00:00 0
7f8d44961000-7f8d44986000 r-xp 00000000 08:01 1054409 /lib/x86_64-linux-gnu/libselinux.so.1
7f8d44986000-7f8d44b85000 ---p 00025000 08:01 1054409 /lib/x86_64-linux-gnu/libselinux.so.1
7f8d44b85000-7f8d44b86000 r--p 00024000 08:01 1054409 /lib/x86_64-linux-gnu/libselinux.so.1
7f8d44b86000-7f8d44b87000 rw-p 00025000 08:01 1054409 /lib/x86_64-linux-gnu/libselinux.so.1
7f8d44b87000-7f8d44b8b000 rw-p 00000000 00:00 0
7f8d44b8b000-7f8d44ba7000 r-xp 00000000 08:01 1054424 /lib/x86_64-linux-gnu/libz.so.1.2.11
7f8d44ba7000-7f8d44da6000 ---p 0001c000 08:01 1054424 /lib/x86_64-linux-gnu/libz.so.1.2.11
7f8d44da6000-7f8d44da7000 r--p 0001b000 08:01 1054424 /lib/x86_64-linux-gnu/libz.so.1.2.11
7f8d44da7000-7f8d44da8000 rw-p 0001c000 08:01 1054424 /lib/x86_64-linux-gnu/libz.so.1.2.11
7f8d44da8000-7f8d44dae000 r--p 00000000 08:01 1054404 /lib/x86_64-linux-gnu/libpthread-2.28.so
7f8d44dae000-7f8d44dbd000 r-xp 00006000 08:01 1054404 /lib/x86_64-linux-gnu/libpthread-2.28.so
7f8d44dbd000-7f8d44dc3000 r--p 00015000 08:01 1054404 /lib/x86_64-linux-gnu/libpthread-2.28.so
7f8d44dc3000-7f8d44dc4000 r--p 0001a000 08:01 1054404 /lib/x86_64-linux-gnu/libpthread-2.28.so
7f8d44dc4000-7f8d44dc5000 rw-p 0001b000 08:01 1054404 /lib/x86_64-linux-gnu/libpthread-2.28.so
7f8d44dc5000-7f8d44dc9000 rw-p 00000000 00:00 0
7f8d44dc9000-7f8d44dca000 r--p 00000000 08:01 396434 /usr/lib/x86_64-linux-gnu/libgmodule-2.0.so.0.5800.1
7f8d44dca000-7f8d44dcc000 r-xp 00001000 08:01 396434 /usr/lib/x86_64-linux-gnu/libgmodule-2.0.so.0.5800.1
7f8d44dcc000-7f8d44dcd000 r--p 00003000 08:01 396434 /usr/lib/x86_64-linux-gnu/libgmodule-2.0.so.0.5800.1
7f8d44dcd000-7f8d44dce000 r--p 00003000 08:01 396434 /usr/lib/x86_64-linux-gnu/libgmodule-2.0.so.0.5800.1
7f8d44dce000-7f8d44dcf000 rw-p 00004000 08:01 396434 /usr/lib/x86_64-linux-gnu/libgmodule-2.0.so.0.5800.1
7f8d44dcf000-7f8d44df1000 r--p 00000000 08:01 1054333 /lib/x86_64-linux-gnu/libc-2.28.so
7f8d44df1000-7f8d44f62000 r-xp 00022000 08:01 1054333 /lib/x86_64-linux-gnu/libc-2.28.so
7f8d44f62000-7f8d44fae000 r--p 00193000 08:01 1054333 /lib/x86_64-linux-gnu/libc-2.28.so
7f8d44fae000-7f8d44faf000 ---p 001df000 08:01 1054333 /lib/x86_64-linux-gnu/libc-2.28.so
7f8d44faf000-7f8d44fb3000 r--p 001df000 08:01 1054333 /lib/x86_64-linux-gnu/libc-2.28.so
7f8d44fb3000-7f8d44fb5000 rw-p 001e3000 08:01 1054333 /lib/x86_64-linux-gnu/libc-2.28.so
7f8d44fb5000-7f8d44fb9000 rw-p 00000000 00:00 0
7f8d44fb9000-7f8d44fbb000 r--p 00000000 08:01 409807 /usr/lib/x86_64-linux-gnu/libplist.so.3.1.0
7f8d44fbb000-7f8d44fc4000 r-xp 00002000 08:01 409807 /usr/lib/x86_64-linux-gnu/libplist.so.3.1.0
7f8d44fc4000-7f8d44fc7000 r--p 0000b000 08:01 409807 /usr/lib/x86_64-linux-gnu/libplist.so.3.1.0
7f8d44fc7000-7f8d44fc8000 r--p 0000d000 08:01 409807 /usr/lib/x86_64-linux-gnu/libplist.so.3.1.0
7f8d44fc8000-7f8d44fc9000 rw-p 0000e000 08:01 409807 /usr/lib/x86_64-linux-gnu/libplist.so.3.1.0
7f8d44fc9000-7f8d44feb000 r-xp 00000000 08:01 409630 /usr/lib/x86_64-linux-gnu/libimobiledevice.so.6.0.0
7f8d44feb000-7f8d451ea000 ---p 00022000 08:01 409630 /usr/lib/x86_64-linux-gnu/libimobiledevice.so.6.0.0
7f8d451ea000-7f8d451eb000 r--p 00021000 08:01 409630 /usr/lib/x86_64-linux-gnu/libimobiledevice.so.6.0.0
7f8d451eb000-7f8d451ec000 rw-p 00022000 08:01 409630 /usr/lib/x86_64-linux-gnu/libimobiledevice.so.6.0.0
7f8d451ec000-7f8d451ee000 rw-p 00000000 00:00 0
7f8d451ee000-7f8d45209000 r--p 00000000 08:01 396432 /usr/lib/x86_64-linux-gnu/libglib-2.0.so.0.5800.1
7f8d45209000-7f8d45286000 r-xp 0001b000 08:01 396432 /usr/lib/x86_64-linux-gnu/libglib-2.0.so.0.5800.1
7f8d45286000-7f8d45308000 r--p 00098000 08:01 396432 /usr/lib/x86_64-linux-gnu/libglib-2.0.so.0.5800.1
7f8d45308000-7f8d45309000 r--p 00119000 08:01 396432 /usr/lib/x86_64-linux-gnu/libglib-2.0.so.0.5800.1
7f8d45309000-7f8d4530a000 rw-p 0011a000 08:01 396432 /usr/lib/x86_64-linux-gnu/libglib-2.0.so.0.5800.1
7f8d4530a000-7f8d4530b000 rw-p 00000000 00:00 0
7f8d4530b000-7f8d45316000 r--p 00000000 08:01 396833 /usr/lib/x86_64-linux-gnu/libgobject-2.0.so.0.5800.1
7f8d45316000-7f8d45347000 r-xp 0000b000 08:01 396833 /usr/lib/x86_64-linux-gnu/libgobject-2.0.so.0.5800.1
7f8d45347000-7f8d4535d000 r--p 0003c000 08:01 396833 /usr/lib/x86_64-linux-gnu/libgobject-2.0.so.0.5800.1
7f8d4535d000-7f8d4535e000 r--p 00051000 08:01 396833 /usr/lib/x86_64-linux-gnu/libgobject-2.0.so.0.5800.1
7f8d4535e000-7f8d4535f000 rw-p 00052000 08:01 396833 /usr/lib/x86_64-linux-gnu/libgobject-2.0.so.0.5800.1
7f8d4535f000-7f8d45368000 r-xp 00000000 08:01 409594 /usr/lib/x86_64-linux-gnu/libgudev-1.0.so.0.2.0
7f8d45368000-7f8d45567000 ---p 00009000 08:01 409594 /usr/lib/x86_64-linux-gnu/libgudev-1.0.so.0.2.0
7f8d45567000-7f8d45568000 r--p 00008000 08:01 409594 /usr/lib/x86_64-linux-gnu/libgudev-1.0.so.0.2.0
7f8d45568000-7f8d45569000 rw-p 00009000 08:01 409594 /usr/lib/x86_64-linux-gnu/libgudev-1.0.so.0.2.0
7f8d45569000-7f8d45580000 r-xp 00000000 08:01 1054420 /lib/x86_64-linux-gnu/libusb-1.0.so.0.1.0
7f8d45580000-7f8d45780000 ---p 00017000 08:01 1054420 /lib/x86_64-linux-gnu/libusb-1.0.so.0.1.0
7f8d45780000-7f8d45781000 r--p 00017000 08:01 1054420 /lib/x86_64-linux-gnu/libusb-1.0.so.0.1.0
7f8d45781000-7f8d45782000 rw-p 00018000 08:01 1054420 /lib/x86_64-linux-gnu/libusb-1.0.so.0.1.0
7f8d45782000-7f8d457b7000 r--p 00000000 08:01 396430 /usr/lib/x86_64-linux-gnu/libgio-2.0.so.0.5800.1
7f8d457b7000-7f8d458a0000 r-xp 00035000 08:01 396430 /usr/lib/x86_64-linux-gnu/libgio-2.0.so.0.5800.1
7f8d458a0000-7f8d4591c000 r--p 0011e000 08:01 396430 /usr/lib/x86_64-linux-gnu/libgio-2.0.so.0.5800.1
7f8d4591c000-7f8d4591d000 ---p 0019a000 08:01 396430 /usr/lib/x86_64-linux-gnu/libgio-2.0.so.0.5800.1
7f8d4591d000-7f8d45924000 r--p 0019a000 08:01 396430 /usr/lib/x86_64-linux-gnu/libgio-2.0.so.0.5800.1
7f8d45924000-7f8d45925000 rw-p 001a1000 08:01 396430 /usr/lib/x86_64-linux-gnu/libgio-2.0.so.0.5800.1
7f8d45925000-7f8d45927000 rw-p 00000000 00:00 0
7f8d45927000-7f8d4594b000 r-xp 00000000 08:01 409945 /usr/lib/x86_64-linux-gnu/libupower-glib.so.3.0.1
7f8d4594b000-7f8d45b4b000 ---p 00024000 08:01 409945 /usr/lib/x86_64-linux-gnu/libupower-glib.so.3.0.1
7f8d45b4b000-7f8d45b4d000 r--p 00024000 08:01 409945 /usr/lib/x86_64-linux-gnu/libupower-glib.so.3.0.1
7f8d45b4d000-7f8d45b4e000 rw-p 00026000 08:01 409945 /usr/lib/x86_64-linux-gnu/libupower-glib.so.3.0.1
7f8d45b4e000-7f8d45b50000 rw-p 00000000 00:00 0
7f8d45b63000-7f8d45b6a000 r--s 00000000 08:01 527101 /usr/lib/x86_64-linux-gnu/gconv/gconv-modules.cache
7f8d45b6a000-7f8d45b6b000 r--p 00000000 08:01 1054321 /lib/x86_64-linux-gnu/ld-2.28.so
7f8d45b6b000-7f8d45b8b000 r-xp 00001000 08:01 1054321 /lib/x86_64-linux-gnu/ld-2.28.so
7f8d45b8b000-7f8d45b93000 r--p 00021000 08:01 1054321 /lib/x86_64-linux-gnu/ld-2.28.so
7f8d45b93000-7f8d45b94000 r--p 00028000 08:01 1054321 /lib/x86_64-linux-gnu/ld-2.28.so
7f8d45b94000-7f8d45b95000 rw-p 00029000 08:01 1054321 /lib/x86_64-linux-gnu/ld-2.28.so
7f8d45b95000-7f8d45b96000 rw-p 00000000 00:00 0
7fffa75d8000-7fffa75f9000 rw-p 00000000 00:00 0 [stack]
7fffa75fb000-7fffa75fe000 r--p 00000000 00:00 0 [vvar]
7fffa75fe000-7fffa7600000 r-xp 00000000 00:00 0 [vdso]
ffffffffff600000-ffffffffff601000 r-xp 00000000 00:00 0 [vsyscall]The article explains basics of memory management, reveals concept of virtual addresses and describes roles of different memory segments. It's important to keep in mind problems that can occur because of stack or heap expanding.
HackerRank link.
Internet 101 videos are extremely teachable and information presented in nice-looking form, good for me I'm already familiar with terminology of Internet and TCP/IP protocols (thanks NAU, very cool).
How DNS Works. Education in the form of comics? yes please. In entertaining form it explains how DNS works and what a journey lies behind a DNS query. Main concepts that I learned is that every unit in this DNS-finding sequence doesn't need to know every address in the Internet, it just knows where to ask, and another thing that helps is cash where machine can look before asking.
Networking for Web Developers Throughout the course were covered CLI commands to interact with network, were revealed some problems existing in Web and protocols like HTTP and TCP were explained. TCP flag is a part of the TCP packet and used to communicate between sender and receiver in the form of boolean value. I find this familiar to the conversation of two people with walkie-talkie. They need some code phrases to signal start or end of conversation, acknowledgment of data delivery like [S],[F] and [.] flags in TCP packet.
Good to remember:
- traceroute - tell us how many hops are between you and destination address.
- ttl - time to live
Firewall is one of the middlebox devices that performs filtering function between client and server, it can also change traffic, e.g. replace content of a web-page in politic or social purposes. NAT is another example of middlebox devices, they act as a bridge between outside and inside network, several devices in local network can share the same "outside" address, usually our home routers perform both firewall and NAT functions.
⌨️ Practical task on python - port-sniffer ⌨️
📚 Udacity networking course complete 📚
HTTP is a stateless protocol in which communication between host and client occurs via request/response pair. Action on a host is determined by a special verbs, most popular are GET, POST, PUT and DELETE. Server responds with message payloads and status codes that help client to understand server response.
Using cookies is one of the ways to identify user, they allow the server to attach arbitrary information for outgoing responses.
The second part of article introduced more detailed information about http connections, namely process of user identification and authentication, secure protocol and certificates and concept of caching that saves time, cost and improve web-browsing experience.
curl https://api.github.com/users/AQuaZar
{ "login": "AQuaZar", "id": 36030534, "node_id": "MDQ6VXNlcjM2MDMwNTM0", "avatar_url": "https://avatars3.githubusercontent.com/u/36030534?v=4", "gravatar_id": "", "url": "https://api.github.com/users/AQuaZar", "html_url": "https://github.com/AQuaZar", "followers_url": "https://api.github.com/users/AQuaZar/followers", "following_url": "https://api.github.com/users/AQuaZar/following{/other_user}", "gists_url": "https://api.github.com/users/AQuaZar/gists{/gist_id}", "starred_url": "https://api.github.com/users/AQuaZar/starred{/owner}{/repo}", "subscriptions_url": "https://api.github.com/users/AQuaZar/subscriptions", "organizations_url": "https://api.github.com/users/AQuaZar/orgs", "repos_url": "https://api.github.com/users/AQuaZar/repos", "events_url": "https://api.github.com/users/AQuaZar/events{/privacy}", "received_events_url": "https://api.github.com/users/AQuaZar/received_events", "type": "User", "site_admin": false, "name": null, "company": null, "blog": "", "location": null, "email": null, "hireable": null, "bio": null, "public_repos": 6, "public_gists": 0, "followers": 2, "following": 2, "created_at": "2018-02-01T08:23:23Z", "updated_at": "2019-10-14T14:01:23Z" }curl -i https://api.github.com/users/aquazar
HTTP/1.1 200 OK Date: Mon, 14 Oct 2019 14:06:32 GMT Content-Type: application/json; charset=utf-8 Content-Length: 1249 Server: GitHub.com Status: 200 OK X-RateLimit-Limit: 60 X-RateLimit-Remaining: 50 X-RateLimit-Reset: 1571065200 Cache-Control: public, max-age=60, s-maxage=60 Vary: Accept ETag: "4afbb5ccf212d758c45dcc5b691369a9" Last-Modified: Mon, 14 Oct 2019 14:01:23 GMT X-GitHub-Media-Type: github.v3; format=json Access-Control-Expose-Headers: ETag, Link, Location, Retry-After, X-GitHub-OTP, X-RateLimit-Limit, X-RateLimit-Remaining, X-RateLimit-Reset, X-OAuth-Scopes, X-Accepted-OAuth-Scopes, X-Poll-Interval, X-GitHub-Media-Type Access-Control-Allow-Origin: * Strict-Transport-Security: max-age=31536000; includeSubdomains; preload X-Frame-Options: deny X-Content-Type-Options: nosniff X-XSS-Protection: 1; mode=block Referrer-Policy: origin-when-cross-origin, strict-origin-when-cross-origin Content-Security-Policy: default-src 'none' Vary: Accept-Encoding X-GitHub-Request-Id: C702:1482B:4E3C9F8:5E97CD2:5DA480E8 { "login": "AQuaZar", "id": 36030534, "node_id": "MDQ6VXNlcjM2MDMwNTM0", "avatar_url": "https://avatars3.githubusercontent.com/u/36030534?v=4", "gravatar_id": "", "url": "https://api.github.com/users/AQuaZar", "html_url": "https://github.com/AQuaZar", "followers_url": "https://api.github.com/users/AQuaZar/followers", "following_url": "https://api.github.com/users/AQuaZar/following{/other_user}", "gists_url": "https://api.github.com/users/AQuaZar/gists{/gist_id}", "starred_url": "https://api.github.com/users/AQuaZar/starred{/owner}{/repo}", "subscriptions_url": "https://api.github.com/users/AQuaZar/subscriptions", "organizations_url": "https://api.github.com/users/AQuaZar/orgs", "repos_url": "https://api.github.com/users/AQuaZar/repos", "events_url": "https://api.github.com/users/AQuaZar/events{/privacy}", "received_events_url": "https://api.github.com/users/AQuaZar/received_events", "type": "User", "site_admin": false, "name": null, "company": null, "blog": "", "location": null, "email": null, "hireable": null, "bio": null, "public_repos": 6, "public_gists": 0, "followers": 2, "following": 2, "created_at": "2018-02-01T08:23:23Z", "updated_at": "2019-10-14T14:01:23Z" }curl https://api.github.com/gists/starred
{ "message": "Requires authentication", "documentation_url": "https://developer.github.com/v3/#authentication" }curl --user "AQuaZar:dsagadgs" https://api.github.com/gists/starred
{ "message": "Bad credentials", "documentation_url": "https://developer.github.com/v3" }curl --user "AQuaZar" https://api.github.com/gists/starred
Enter host password for user 'AQuaZar': [ { "url": "https://api.github.com/gists/e0defc252f665b2b51e8", "forks_url": "https://api.github.com/gists/e0defc252f665b2b51e8/forks", "commits_url": "https://api.github.com/gists/e0defc252f665b2b51e8/commits", "id": "e0defc252f665b2b51e8", "node_id": "MDQ6R2lzdGUwZGVmYzI1MmY2NjViMmI1MWU4", "git_pull_url": "https://gist.github.com/e0defc252f665b2b51e8.git", "git_push_url": "https://gist.github.com/e0defc252f665b2b51e8.git", "html_url": "https://gist.github.com/e0defc252f665b2b51e8", "files": { "twitch.py": { "filename": "twitch.py", "type": "application/x-python", "language": "Python", "raw_url": "https://gist.githubusercontent.com/StepS-/e0defc252f665b2b51e8/raw/43b4d5616d2ea60102a8efef779c679b86d53cf7/twitch.py", "size": 8007 } }, "public": true, "created_at": "2015-06-18T02:09:15Z", "updated_at": "2019-10-14T14:04:41Z", "description": "", "comments": 0, "user": null, "comments_url": "https://api.github.com/gists/e0defc252f665b2b51e8/comments", "owner": { "login": "StepS-", "id": 5569139, "node_id": "MDQ6VXNlcjU1NjkxMzk=", "avatar_url": "https://avatars3.githubusercontent.com/u/5569139?v=4", "gravatar_id": "", "url": "https://api.github.com/users/StepS-", "html_url": "https://github.com/StepS-", "followers_url": "https://api.github.com/users/StepS-/followers", "following_url": "https://api.github.com/users/StepS-/following{/other_user}", "gists_url": "https://api.github.com/users/StepS-/gists{/gist_id}", "starred_url": "https://api.github.com/users/StepS-/starred{/owner}{/repo}", "subscriptions_url": "https://api.github.com/users/StepS-/subscriptions", "organizations_url": "https://api.github.com/users/StepS-/orgs", "repos_url": "https://api.github.com/users/StepS-/repos", "events_url": "https://api.github.com/users/StepS-/events{/privacy}", "received_events_url": "https://api.github.com/users/StepS-/received_events", "type": "User", "site_admin": false }, "truncated": false } ]Q&A
-
Name at least three possible negative consequences of not using https.
- Absence of privacy, client's private data can be leaked.
- Messages between client and server can intercepted and changed or copied in own purposes.
- Unreliability of host, server can be uncertified and pretend to be another web-site.
-
Explain the main idea behind public key cryptography in few sentences
- Public key is accessible for everyone and used to decrypt messages encrypted by private key and vice versa. First party encrypts message with own private key and sends to another, since access to private key has only owner it proves authenticity of sender, in its turn, second party encrypts own message (for example key for symmetric encryption) by public key of other party, and by own private key, as result first party will get message that only it can decrypt and authenticity of second party will be proven.
-
You are creating and application for pet clinic. You need to implement the following functionality:
- add new pet
- POST
- Query: application/pets
- Body: name, age, breed, owner's name, medical history
- Server response: 200 OK
- search pet by name
- GET method with pet name as query params
- Server response: 200 OK, resource in body
- change name of an existing pet
- PUT with pets name in request payload
- Server response: 200 OK
- add new info about pet's health
- POST or PUT
- assign a pet to a particular doctor in the clinic
- POST or PUT
- register an appointment for a pet.
- POST
- Query: URI of pet's appointments
- Body: info about pet, doctor and appointment date and time
- Server response: 200 OK
Design patterns are solutions to recurring problems; guidelines on how to tackle certain problems
Repository on github that can be used as useful reminder of different design patterns. I clarified to myself that patterns can be classified on:
- Creational, that are focused on how to instantiate an object;
- Structural, concerned how entities can use each other in structural context;
- Behavioral cover communication and roles between entities;
The point of the first 14 lessons is more about how to represent, express and describe architecture of software, whereas next lessons are closer to design itself and lesson 27 is quintessence of design patterns and is most coupled with current section.
What was new to me:
- UML - Unified Modeling Language, used to visualize and represent the way system was designed.
- OCL - provides constraint and object query expressions that cannot be expressed by UML.
- How to analyze technical task by breaking up it on a lexical pieces and building UML class-diagram from them.
Design process in a nutshell:
- Phase 0 - Understand the system and it's interactions with external actors
- Phase 1 - Divide the system into components and analyze interactions that will have to occur among the components and define constraints.
- Phase 2 - Select architectural style
After completing this course I can definitely say that I will not remember all of the material covered, but as was mentioned in this course that its hard to implement patterns and software architecture principles by theoretical learning, is more about using your own experience. So this course gave me awareness about patterns and aspects of system design but my practical path is yet to come.
📚 Software architecture course complete 📚
Stack is a linear data structure that uses LIFO (last in, first out) principle, data is pushed to stack or popped only from top of it.
- Pros of stack: O(1) insert/remove element complexity, it could be implemented by linked list (so dynamic memory allocation).
- Cons of stack: can occur stack overflow and cause memory leak, no random access, inconvenient for search, sort e.t.c.
Queue is very similar to stack but uses another method to access and add data elements -- FIFO (first in, first out).
Linked List is structure constructed from nodes, each node has some data and reference to the next node, last node points to nothing (None,null). It is dynamic data structure, so addresses allocated for elements does not have to be in one place, but could be spread out across memory. Linked list have many variations, like in stack data could be inserted only from head (singly linked list) or alike from both ends (doubly linked list) or even could be circular. This structure is efficient in insertion or removing from ends, but slow in traversing it's content.
Tree is non-linear data-structure, like linked lists it consists of nodes, but node can have links to multiple other nodes. Every tree must have a root that is a top-most node in the tree, and also it has no parents :(. Examples of a tree is a DOM in HTML and file system.
⌨️ Practical task on python - stack/linked list app + API ⌨️
Unix file system is a tree-like structure that contains directories, which in the turn contain files. A top-most directory is called "root". Also there are different types of files, some of them used to represent devices, some for processes or commands interconnection and basic files with data, text or programs.
File permission helps to increase control on file access. Basic permissions are: read, write, execute. These three rights can be set for three types of users: owner, group, others.
To change permissions chmod command is used. Example of using: chmod 361 somefile.txt. If we represent 361 in binary form we will get: 011 110 001 that interpreters as -wx rw- --x, write and execute permission for owner, read and write permission for member of a group that a file belongs to and execute permission for others.
Working With Files in Python article explains how to work with files in python programs, instruments similar to shell utilities can be found in libraries like os, pathlib, shutil.
⌨️ Practical part - secret.txt, file system task. ⌨️
As I understood, GIL is a headache for python developers. It is a simple solution for a complex problem but has a tradeoff in multi-core performance, because of GIL, only one thread can be executed at a time.
Asyncio gives us some sort of concurrency, moreover it is not dealing with GIL, all is legit - one process, one thread, what's the trick? The main 'ho ho' of the asyncio is to use downtime of one task and let other task run in the meantime, usually it is useful in the I/O tasks. So what is happening is just switching between tasks back and forth and as result we have pretty sweet time bonus.
DBMS gives possibility to store, manipulate and manage data. It provides data storage in organized manner, security and integrity of data and interaction with user queries. RDBMS is more extended version of DBMS, where data is presented as tables that are directly or indirectly related, and it has concept of keys.
Primary key is used to uniquely identify record in a table.
Foreign key is a column that contains the primary key to another table.
To interact with data in a database we can use SQL that is Structured Query Language. Throughout the course, I used such query statements as:
-
SELECT - this query is used to select data from database, in result the table is returned, there are variety of ways to specify data exactly that we need, also we can count, sort, find min and max from resulting table even faster than programming languages will do;
-
INSERT - very simple query that inputs data to database, we need specify values to insert and column destination;
-
UPDATE - this statement edit the row in the table;
-
DELETE - used to delete records from table, also can be specified by which criteria it should be deleted;
-
GROUP BY - a clause used with aggregate functions to combine data from one or more columns.
-
HAVING limit the results of a query based on an aggregate property.
To select data that is stored in two tables we use JOIN clause. There are several types of joins, the simplest one is a cross-join, where every row of first table is combined with other row of another table, the more useful one is inner join where only such rows are combined where specified column values are the same. Whereas inner join provides us data only if there are matching records in both table, using LEFT or RIGHT outer join we can still have records (from left or right table respectively) even if they don't have accordance in another table.
Normalized forms:
- Amount of columns are have to be the same for all rows.
- All non-key fields are have to be facts about the keys (and not about subset of a key).
- Non-key field cannot be fact about another non-key field.
- Row cannot have two independent multi-valued facts about entity without relations with each other.
Subqueries concept gives us ability to work with intermediate tables that are results of a query. It is useful if we want to apply query statement to the result of an another query statement.
📚 Intro to Relational Databases, Learn SQL and Khanacademy courses complete 📚
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⌨️ Practical task ⌨️
Schema (MySQL v8.0)
SET GLOBAL sql_mode=(SELECT REPLACE(@@sql_mode,'ONLY_FULL_GROUP_BY',''));
CREATE TABLE IF NOT EXISTS `person` (
`id` INT AUTO_INCREMENT PRIMARY KEY,
`first_name` VARCHAR(255) NOT NULL,
`last_name` VARCHAR(255) NOT NULL,
`created_at` DATETIME DEFAULT NOW(),
`updated_at` DATETIME DEFAULT NOW()
) ENGINE=INNODB;
CREATE TABLE IF NOT EXISTS `item` (
`id` INT AUTO_INCREMENT PRIMARY KEY,
`name` VARCHAR(255) NOT NULL,
`price` DECIMAL(5,2) DEFAULT 0,
`created_at` DATETIME DEFAULT NOW(),
`updated_at` DATETIME DEFAULT NOW()
) ENGINE=INNODB;
CREATE TABLE IF NOT EXISTS `orders` (
`id` INT AUTO_INCREMENT PRIMARY KEY,
`person_id` INT NOT NULL REFERENCES `person`(`id`),
`created_at` DATETIME DEFAULT NOW(),
`updated_at` DATETIME DEFAULT NOW()
) ENGINE=INNODB;
CREATE TABLE IF NOT EXISTS `order_item` (
`id` INT AUTO_INCREMENT PRIMARY KEY,
`order_id` INT NOT NULL REFERENCES `orders`(`id`),
`item_id` INT NOT NULL REFERENCES `item_id`(`id`),
`quantity` INT DEFAULT 1,
`discount` DECIMAL(5,2) DEFAULT 0,
`created_at` DATETIME DEFAULT NOW(),
`updated_at` DATETIME DEFAULT NOW()
) ENGINE=INNODB;
INSERT INTO `person`(`first_name`, `last_name`) VALUES
('Ann', 'Peterson'),
('Josh', 'Harris'),
('Sarah', 'Connor'),
('James', 'Ball');
INSERT INTO `item`(`name`, `price`) VALUES
('TV', 299.99),
('Carrot', 1.25),
('Patrol', 1.41),
('Soap', 0.4),
('Football Tickets', 149),
('T-Shirt', 19.1),
('Playstation 4 Pro', 419.99);
INSERT INTO `orders`(`person_id`) VALUES
(1),
(2),
(4),
(4);
INSERT INTO `order_item`(`order_id`, `item_id`, `quantity`, `discount`) VALUES
(1, 3, 4, 0),
(1, 6, 1, 0),
(2, 1, 1, 11.2),
(2, 7, 1, 15.99),
(3, 4, 3, 0),
(3, 2, 8, 0),
(3, 6, 1, 0),
(4, 5, 1, 1.49);
Query #1
select first_name, last_name,count(distinct orders.id) as total_orders,sum(quantity) as total_items_bought,sum(quantity*(price-discount)) as total_money_spent from person
left join orders on person.id = orders.person_id
left join order_item on orders.id = order_item.order_id
left join item on item.id = order_item.item_id
group by orders.person_id
order by person.id;
| first_name | last_name | total_orders | total_items_bought | total_money_spent |
|---|---|---|---|---|
| Ann | Peterson | 1 | 5 | 24.74 |
| Josh | Harris | 1 | 2 | 692.79 |
| Sarah | Connor | 0 | ||
| James | Ball | 2 | 13 | 177.81 |