NW | 2026-mar-sdc | Zabihollah Namazi | Sprint 2 | shell pipelines

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]' 

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]'    # ^ -> starts line with [A_Z]

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]*$'    # [a-z]* = zero or more lowercase after that , $ = end of this line grep 

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]*$'    # -c to count lines 

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 -k1,1 scores-table.txt  # -k 'column'  starts -k1 and end ,1 column

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  # nr = from largest to smallest 

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  # head -n3 = takes only the first 3 lines

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 | head -n 2 | tail -n 1 # we get first two top and show last one with tail which is second one 

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 -u events.txt # first sort them and then remove dublicates

shell-pipelines/sort-uniq-head-tail/script-06.sh

@@ -5,3 +5,4 @@ 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.
+awk '{print $1}' events.txt | sort | uniq -c 

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.
+tail -n +2 events-with-timestamps.txt | awk '{print $3}' | sort | uniq -c   # tail -n +2 start from second line

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 (.).
+tr '!' '.' < text.txt  # or you can use --> sed 's/!/./g' text.txt

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  # tr 'YyZz' 'ZzYy' → swap letters: Y -> Z , y -> z , Z -> Y , z -> y