diff --git a/individual-shell-tools/ls/script-01.sh b/individual-shell-tools/ls/script-01.sh index 241b62f5..72f2fb4a 100755 --- a/individual-shell-tools/ls/script-01.sh +++ b/individual-shell-tools/ls/script-01.sh @@ -13,3 +13,4 @@ fi # TODO: Write a command to list the files and folders in this directory. # The output should be a list of names including child-directory, script-01.sh, script-02.sh, and more. +ls diff --git a/individual-shell-tools/ls/script-02.sh b/individual-shell-tools/ls/script-02.sh index d0a5a10f..d3717572 100755 --- a/individual-shell-tools/ls/script-02.sh +++ b/individual-shell-tools/ls/script-02.sh @@ -4,3 +4,4 @@ set -euo pipefail # TODO: Write a command which lists all of the files in the directory named child-directory. # The output should be a list of names: helper-1.txt, helper-2.txt, helper-3.txt. +ls child-directory diff --git a/individual-shell-tools/ls/script-03.sh b/individual-shell-tools/ls/script-03.sh index 781216d2..8f0627b5 100755 --- a/individual-shell-tools/ls/script-03.sh +++ b/individual-shell-tools/ls/script-03.sh @@ -5,3 +5,4 @@ set -euo pipefail # TODO: Write a command which _recursively_ lists all of the files and folders in this directory _and_ all of the files inside those folders. # The output should be a list of names including: child-directory, script-01.sh, helper-1.txt (and more). # The formatting of the output doesn't matter. +ls -R diff --git a/individual-shell-tools/ls/script-04.sh b/individual-shell-tools/ls/script-04.sh index 72f3817b..ae225dc8 100755 --- a/individual-shell-tools/ls/script-04.sh +++ b/individual-shell-tools/ls/script-04.sh @@ -16,8 +16,10 @@ echo "First exercise (sorted newest to oldest):" # TODO: Write a command which lists the files in the child-directory directory, one per line, sorted so that the most recently modified file is first. # The output should be a list of names in this order, one per line: helper-3.txt, helper-1.txt, helper-2.txt. +ls -t1 ./child-directory echo "Second exercise (sorted oldest to newest):" # TODO: Write a command which does the same as above, but sorted in the opposite order (oldest first). # The output should be a list of names in this order, one per line: helper-2.txt, helper-1.txt, helper-3.txt. +ls -tr1 child-directory diff --git a/jq/script-01.sh b/jq/script-01.sh index 95827f68..0d69705d 100755 --- a/jq/script-01.sh +++ b/jq/script-01.sh @@ -5,3 +5,4 @@ set -euo pipefail # The input for this script is the person.json file. # TODO: Write a command to output the name of the person. # Your output should be exactly the string "Selma", but should not contain any quote characters. +jq -r '.name' person.json diff --git a/jq/script-02.sh b/jq/script-02.sh index 21544d67..e7c322de 100755 --- a/jq/script-02.sh +++ b/jq/script-02.sh @@ -5,3 +5,5 @@ set -euo pipefail # The input for this script is the person.json file. # TODO: Write a command to output the address of the person, all on one line, with a comma between each line. # Your output should be exactly the string "35 Fashion Street, London, E1 6PX", but should not contain any quote characters. +jq -r '.address | join(", ")' person.json + diff --git a/jq/script-03.sh b/jq/script-03.sh index 3566f03b..d815788e 100755 --- a/jq/script-03.sh +++ b/jq/script-03.sh @@ -5,3 +5,4 @@ set -euo pipefail # The input for this script is the person.json file. # TODO: Write a command to output the name of the person, then a comma, then their profession. # Your output should be exactly the string "Selma, Software Engineer", but should not contain any quote characters. +jq -r '[.name, .profession] | join(", ")' person.json diff --git a/jq/script-04.sh b/jq/script-04.sh index 015997e1..e50f742a 100755 --- a/jq/script-04.sh +++ b/jq/script-04.sh @@ -6,3 +6,4 @@ set -euo pipefail # TODO: Write a command to output just the names of each player, one per line. # Your output should contain 6 lines, each with just one word on it. # Your output should not contain any quote characters. +jq -r '.[].name' scores.json diff --git a/jq/script-05.sh b/jq/script-05.sh index 993fc9ee..ab78fbad 100755 --- a/jq/script-05.sh +++ b/jq/script-05.sh @@ -5,3 +5,4 @@ set -euo pipefail # The input for this script is the scores.json file. # TODO: Write a command to output the names of each player, as well as their city. # Your output should contain 6 lines, each with two words on it. +jq -r '.[] | "\(.name) \(.city)"' scores.json diff --git a/jq/script-06.sh b/jq/script-06.sh index 8b6e74c5..47fee35b 100755 --- a/jq/script-06.sh +++ b/jq/script-06.sh @@ -6,3 +6,4 @@ set -euo pipefail # TODO: Write a command to output just the names of each player along with the score from their first attempt. # Your output should contain 6 lines, each with one word and one number on it. # The first line should be "Ahmed 1" with no quotes. +jq -r '.[] | "\(.name) \(.scores[0])"' scores.json diff --git a/jq/script-07.sh b/jq/script-07.sh index d43f93d1..f20ab3d7 100755 --- a/jq/script-07.sh +++ b/jq/script-07.sh @@ -6,3 +6,4 @@ set -euo pipefail # TODO: Write a command to output just the names of each player along with the score from their last attempt. # Your output should contain 6 lines, each with one word and one number on it. # The first line should be "Ahmed 4" with no quotes. +jq -r '.[] | "\(.name) \(.scores[-1])"' scores.json diff --git a/jq/script-08.sh b/jq/script-08.sh index 6671fd1b..165e67a4 100755 --- a/jq/script-08.sh +++ b/jq/script-08.sh @@ -6,3 +6,4 @@ set -euo pipefail # TODO: Write a command to output just the names of each player along with the number of times they've played the game. # Your output should contain 6 lines, each with one word and one number on it. # The first line should be "Ahmed 3" with no quotes. +jq -r '.[] | "\(.name) \(.scores | length)"' scores.json diff --git a/jq/script-09.sh b/jq/script-09.sh index c2536a53..3ce4c2b7 100755 --- a/jq/script-09.sh +++ b/jq/script-09.sh @@ -6,3 +6,4 @@ set -euo pipefail # TODO: Write a command to output just the names of each player along with the total scores from all of their games added together. # Your output should contain 6 lines, each with one word and one number on it. # The first line should be "Ahmed 15" with no quotes. +jq -r '.[] | "\(.name) \(.scores | add)"' scores.json diff --git a/jq/script-10.sh b/jq/script-10.sh index 8e9d75f0..e1334079 100755 --- a/jq/script-10.sh +++ b/jq/script-10.sh @@ -5,3 +5,4 @@ set -euo pipefail # The input for this script is the scores.json file. # TODO: Write a command to output the total of adding together all players' first scores. # Your output should be exactly the number 54. +jq '[.[].scores[0]] | add' scores.json diff --git a/jq/script-11.sh b/jq/script-11.sh index d2337a6b..943b36a3 100755 --- a/jq/script-11.sh +++ b/jq/script-11.sh @@ -5,3 +5,4 @@ set -euo pipefail # The input for this script is the scores.json file. # TODO: Write a command to output the total of adding together all scores from all games from all players. # Your output should be exactly the number 164. +jq '[.[].scores[]] | add' scores.json diff --git a/number-systems/README.md b/number-systems/README.md index 77a3bde9..d33b21c9 100644 --- a/number-systems/README.md +++ b/number-systems/README.md @@ -5,61 +5,67 @@ Do not convert any binary numbers to decimal when solving a question unless the The goal of these exercises is for you to gain an intuition for binary numbers. Using tools to solve the problems defeats the point. Convert the decimal number 14 to binary. -Answer: +Answer: 1110 Convert the binary number 101101 to decimal: -Answer: +Answer:32,8,4,1 = 45 Which is larger: 1000 or 0111? -Answer: +Answer: 1000 is larger since the left most digit is 1 compared to the other number. Which is larger: 00100 or 01011? -Answer: +Answer: 01011 is larger What is 10101 + 01010? -Answer: +Answer: 1111 What is 10001 + 10001? -Answer: +Answer: 100010 What's the largest number you can store with 4 bits, if you want to be able to represent the number 0? -Answer: + +Answer1: If representing 0 means having 0000 AS A POSSIBLE NUMBER in the range of 0 to largest number produced by four digits, then the largest possible number is when all the digits are one which makes 1111 the largest number. + +Answer2: If it means having 0 in one of the digits as a possible occurrence, then the largest possible number produced when zero goes to the last digit to have the least effect which 1110 the largest number. + How many bits would you need in order to store the numbers between 0 and 255 inclusive? -Answer: +Answer: since 256 is 2^8 the biggest number of digits with 255 inclusive is made when we have digits. How many bits would you need in order to store the numbers between 0 and 3 inclusive? -Answer: +Answer: 2 bits How many bits would you need in order to store the numbers between 0 and 1000 inclusive? -Answer: +Answer: 10 bits. since 2^n - 1 = the biggest number with n bits. How can you test if a binary number is a power of two (e.g. 1, 2, 4, 8, 16, ...)? -Answer: +Answer: only of it has only 1 bit as 1 and the rest are zeros Convert the decimal number 14 to hex. -Answer: +Answer: it is E Convert the decimal number 386 to hex. -Answer: +Answer: 281 Convert the hex number 386 to decimal. -Answer: +Answer:6*(16^0)+8*(16^1)+3*(16^2) = 902 Convert the hex number B to decimal. -Answer: +Answer: 11 If reading the byte 0x21 as a number, what decimal number would it mean? -Answer: +Answer: 21hex = 2(16^1)+1(16^0) = 33 If reading the byte 0x21 as an ASCII character, what character would it mean? -Answer: +Answer: ! -If reading the byte 0x21 as a greyscale colour, as described in "Approaches for Representing Colors and Images", what colour would it mean? -Answer: +If reading the byte 0x21 as a gray scale colour, as described in "Approaches for Representing Colors and Images", what color would it mean? +Answer: Since hex21 is 33 in decimal and we have a range of 0(black) to 255(white) in decimal, then 33 is relatively close to zero. So it the gray scale it a dark grey If reading the bytes 0xAA00FF as an RGB colour, as described in "Approaches for Representing Colors and Images", what colour would it mean? -Answer: +Answer: Each set of 2 hex digits stands for each of primary colors in the following order: + +RRGGBB: comparing it to AA00FF means that we don't have any greens. so we would have a mixture of blue and red. So eventually we have shade of purpule If reading the bytes 0xAA00FF as a sequence of three one-byte decimal numbers, what decimal numbers would they be? -Answer: +Answer: 170, 0 , 255 diff --git a/shell-pipelines/ls-grep/script-01.sh b/shell-pipelines/ls-grep/script-01.sh index 8c7d968a..b77993b2 100755 --- a/shell-pipelines/ls-grep/script-01.sh +++ b/shell-pipelines/ls-grep/script-01.sh @@ -4,3 +4,4 @@ set -euo pipefail # TODO: Write a command to output the names of the files in the sample-files directory whose name contains at least one upper case letter. # Your output should contain 11 files. +ls sample-files | grep '[A-Z]' diff --git a/shell-pipelines/ls-grep/script-02.sh b/shell-pipelines/ls-grep/script-02.sh index 16f5f71d..4fa4206c 100755 --- a/shell-pipelines/ls-grep/script-02.sh +++ b/shell-pipelines/ls-grep/script-02.sh @@ -4,3 +4,4 @@ set -euo pipefail # TODO: Write a command to output the names of the files in the sample-files directory whose name starts with an upper case letter. # Your output should contain 10 files. +ls sample-files | grep '^[A-Z]' diff --git a/shell-pipelines/ls-grep/script-03.sh b/shell-pipelines/ls-grep/script-03.sh index a302ab03..9b79f1c8 100755 --- a/shell-pipelines/ls-grep/script-03.sh +++ b/shell-pipelines/ls-grep/script-03.sh @@ -4,3 +4,4 @@ set -euo pipefail # TODO: Write a command to output the names of the files in the sample-files directory whose name starts with an upper case letter and doesn't contain any other upper case letters. # Your output should contain 7 files. +ls sample-files | grep '^[A-Z][^A-Z]*$' diff --git a/shell-pipelines/ls-grep/script-04.sh b/shell-pipelines/ls-grep/script-04.sh index c000b7e3..7ece87cd 100755 --- a/shell-pipelines/ls-grep/script-04.sh +++ b/shell-pipelines/ls-grep/script-04.sh @@ -4,3 +4,4 @@ set -euo pipefail # TODO: Write a command to count the number of files in the sample-files directory whose name starts with an upper case letter and doesn't contain any other upper case letters. # Your output should be the number 7. +ls sample-files | grep -c '^[A-Z][^A-Z]*$' diff --git a/shell-pipelines/sort-uniq-head-tail/script-01.sh b/shell-pipelines/sort-uniq-head-tail/script-01.sh index 171e1f98..845ad89d 100755 --- a/shell-pipelines/sort-uniq-head-tail/script-01.sh +++ b/shell-pipelines/sort-uniq-head-tail/script-01.sh @@ -5,3 +5,4 @@ set -euo pipefail # The input for this script is the scores-table.txt file. # TODO: Write a command to output scores-table.txt, with lines sorted by the person's name. # The first line of your output should be "Ahmed London 1 10 4" (with no quotes). And the third line should be "Chandra Birmingham 12 6". +sort scores-table.txt diff --git a/shell-pipelines/sort-uniq-head-tail/script-02.sh b/shell-pipelines/sort-uniq-head-tail/script-02.sh index 29c3c252..e0281500 100755 --- a/shell-pipelines/sort-uniq-head-tail/script-02.sh +++ b/shell-pipelines/sort-uniq-head-tail/script-02.sh @@ -5,3 +5,4 @@ set -euo pipefail # The input for this script is the scores-table.txt file. # TODO: Write a command to output scores-table.txt, with lines sorted by the person's first score, descending. # The first line of your output should be "Basia London 22 9 6" (with no quotes). +sort -k3,3nr scores-table.txt diff --git a/shell-pipelines/sort-uniq-head-tail/script-03.sh b/shell-pipelines/sort-uniq-head-tail/script-03.sh index bcbaf342..01e6b4d0 100755 --- a/shell-pipelines/sort-uniq-head-tail/script-03.sh +++ b/shell-pipelines/sort-uniq-head-tail/script-03.sh @@ -8,3 +8,4 @@ set -euo pipefail # Basia London 22 9 6 # Piotr Glasgow 15 2 25 11 8 # Chandra Birmingham 12 6 +sort -k3,3nr scores-table.txt | head -n 3 diff --git a/shell-pipelines/sort-uniq-head-tail/script-04.sh b/shell-pipelines/sort-uniq-head-tail/script-04.sh index 65a5cfba..a42bac98 100755 --- a/shell-pipelines/sort-uniq-head-tail/script-04.sh +++ b/shell-pipelines/sort-uniq-head-tail/script-04.sh @@ -5,3 +5,4 @@ set -euo pipefail # The input for this script is the scores-table.txt file. # TODO: Write a command to output scores-table.txt, with shows the line for the player whose first score was the second highest. # Your output should be: "Piotr Glasgow 15 2 25 11 8" (without quotes). +sort -k3,3nr scores-table.txt | sed -n '2p' diff --git a/shell-pipelines/sort-uniq-head-tail/script-05.sh b/shell-pipelines/sort-uniq-head-tail/script-05.sh index a93cd9f9..8eba57e3 100755 --- a/shell-pipelines/sort-uniq-head-tail/script-05.sh +++ b/shell-pipelines/sort-uniq-head-tail/script-05.sh @@ -6,3 +6,4 @@ set -euo pipefail # TODO: Write a command to show a list of all events that have happened, without duplication. # The order they're displayed doesn't matter, but we never want to see the same event listed twice. # Your output should contain 6 lines. +sort events.txt | uniq diff --git a/shell-pipelines/sort-uniq-head-tail/script-06.sh b/shell-pipelines/sort-uniq-head-tail/script-06.sh index 715c7ae5..1c628aa7 100755 --- a/shell-pipelines/sort-uniq-head-tail/script-06.sh +++ b/shell-pipelines/sort-uniq-head-tail/script-06.sh @@ -5,3 +5,5 @@ set -euo pipefail # The input for this script is the events.txt file. # TODO: Write a command to show how many times anyone has entered and exited. # It should be clear from your script's output that there have been 5 Entry events and 4 Exit events. + +grep -oE 'Entry|Exit' events.txt | sort | uniq -c diff --git a/shell-pipelines/sort-uniq-head-tail/script-07.sh b/shell-pipelines/sort-uniq-head-tail/script-07.sh index 7fd07e1f..f65fed47 100755 --- a/shell-pipelines/sort-uniq-head-tail/script-07.sh +++ b/shell-pipelines/sort-uniq-head-tail/script-07.sh @@ -6,3 +6,4 @@ set -euo pipefail # TODO: Write a command to show how many times anyone has entered and exited. # It should be clear from your script's output that there have been 5 Entry events and 4 Exit events. # The word "Event" should not appear in your script's output. +awk '{print $3}' events-with-timestamps.txt | grep -E 'Entry|Exit' | sort | uniq -c diff --git a/shell-pipelines/tr/script-01.sh b/shell-pipelines/tr/script-01.sh index 8bb0211e..fe2acd5d 100755 --- a/shell-pipelines/tr/script-01.sh +++ b/shell-pipelines/tr/script-01.sh @@ -6,3 +6,4 @@ set -euo pipefail # The author got feedback that they're using too many exclamation marks (!). # # TODO: Write a command to output the contents of text.txt with every exclamation mark (!) replaced with a full-stop (.). +sed 's/!/./g' text.txt diff --git a/shell-pipelines/tr/script-02.sh b/shell-pipelines/tr/script-02.sh index cf3a503a..8598e779 100755 --- a/shell-pipelines/tr/script-02.sh +++ b/shell-pipelines/tr/script-02.sh @@ -7,3 +7,4 @@ set -euo pipefail # so every Y should be a Z, and every Z should be a Y! # # TODO: Write a command to output the contents of text.txt with every Y and Z swapped (both upper and lower case). +tr 'yYzZ' 'zZyY' < text.txt