Answering all exercises for ls-grep folder

Author: SaraTahir28

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]'

shell-pipelines/ls-grep/script-03.sh

@@ -4,3 +4,6 @@ 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]*S A character that is not an uppercase letter ^ inside brackets means negation, * shows zero occurrences of it and $ ensures we are matching the whole file name

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]*$'