Update bash cheatsheet

resources/ansible.md

@@ -1,20 +1,19 @@
 ## Ansible
 
-### Videos
+### Learn Ansible
 
 Name | Comments
 :------ |:--------:
 [Ansible 101 - Jeff Geerling](https://www.youtube.com/watch?v=goclfp6a2IQ&list=RDCMUCR-DXc1voovS8nhAvccRZhg&index=1) | Comprehensive practical way to learn Ansible
 [What is Ansible? - TechWorld with Nana](https://www.youtube.com/watch?v=1id6ERvfozo) | High-level short overview of Ansible
-[How to write your first Ansible playbook](https://www.youtube.com/watch?v=BeYUQaFS-vg) | Practical video on how to write a playbook in Ansible
+[Learning Ansible basics - Red Hat](https://www.redhat.com/en/topics/automation/learning-ansible-tutorial) | Red Hat's guide on how to learn Ansible basics + links to the content itself
+[Introduction to Ansible - 2021](https://medium.com/@bagusays/introduction-to-ansible-82f2bc12cd87) |
 
 ### Articles
 
 Name | Comments
 :------ |:--------:
-[Learning Ansible basics - Red Hat](https://www.redhat.com/en/topics/automation/learning-ansible-tutorial) | Red Hat's guide on how to learn Ansible basics + links to the content itself
 [Writing reliable Ansible Playbooks - 2021](https://dev.to/xlab_si/writing-reliable-ansible-playbooks-295i) | 
-[Introduction to Ansible - 2021](https://medium.com/@bagusays/introduction-to-ansible-82f2bc12cd87) |
 [A CI/CD Pipeline Project for a Trunk-Based Development Strategy in a Kubernetes Environment](https://medium.com/swlh/a-ci-cd-pipeline-project-for-a-trunk-based-development-strategy-in-a-kubernetes-environment-c4ffea9700fe) |
 
 ### Books

resources/aws.md

@@ -1,5 +1,12 @@
 # AWS
 
+## Infrastructure
+
+Name | Comments
+:------|:------:
+[infrastructure.aws](https://infrastructure.aws) | AWS Infrastructure Overview
+[Regions and Availability Zones](https://aws.amazon.com/about-aws/global-infrastructure/regional-product-services) | See services list per region and AZ
+
 ## Tools and Projects
 
 Name | Comments
@@ -23,7 +30,6 @@ Name | Comments
 [terraformer](https://github.com/GoogleCloudPlatform/terraformer) | "A CLI tool that generates tf/json and tfstate files based on existing infrastructure (reverse Terraform)."
 [terraforming](https://github.com/dtan4/terraforming) | "Export existing AWS resources to Terraform style (tf, tfstate)"
 
-
 ## Videos
 
 Name | Comments

resources/bash.md

@@ -116,6 +116,9 @@ x=$(date) -> Yes :D
 
 * Set variable with default value (string): `x=${x:-'some_default'}`
 * Set variable with default value (variable): `y=${y:-$z}`
+* return value of a program: `$?`
+* Check if variable is empty: `if [ -z "$var" ]; then`
+* Variable length: `${#string}`
 
 #### Arguments
 
@@ -129,6 +132,34 @@ if [ "$#" -lt 1 ]; then
 fi
 ```
 
+* Check if two arguments were passed
+
+```
+if [ "$#" -ne 2 ]; then
+  echo 'Please pass two arguments'
+  exit 1
+fi
+```
+
+* Check if two arguments were passed and both are numbers
+
+```
+re='^[0-9]+$'
+if ! [[ $1 =~ $re && $2 =~ $re ]]; then
+    echo "Oh no...I need two numbers"
+    exit 2
+fi
+```
+
+* Check if arguments' strings length is equal
+
+```
+if [ ${#1} -ne ${#2} ]; then
+  echo 'Not equal`
+  exit 1
+fi
+```
+
 #### Files
 
 * check if file exists
@@ -141,8 +172,67 @@ fi
 ```
 
 * check if directory exists
+
 ```
 DIR=/some/dir
 if [ -d "$DIR"]; then
     echo "$DIR" exists"
 fi
+```
+
+#### Loops
+
+* Iterate over a string: `for i in $(seq 1 ${#1}); do`
+
+#### Arithmetic Operations
+
+* print the sum of two numbers: `echo $((20+17))`
+* Check factor: `if [ $(($1 % 3)) -eq 0 ]; then`
+
+#### Extract Patterns
+
+* Extract date with sed: `echo $line | sed 's/.*\[//g;s/].*//g;s/:.*//g'`
+* Extract first field (space separator) with awk: `echo $line | awk '{print $1}'`
+
+#### Dictionary / Hash Table
+
+* Define a dictionary: `declare -A somedict`
+* Print one value based on given key: `echo ${somedict[some_key]}`
+* Print all the keys of a dictionary: `echo ${!somedict[*]}`
+* Check if key exists: `if [[ -v some_dict[$day] ]]; then`
+
+* Update dict based values and generate top 10:
+
+```
+function update_dict() {
+    declare -A some_dict
+    while read line; do
+        day=$line
+        if [[ -v some_dict[$day] ]]; then
+            some_dict[$day]=$((some_dict[$day]+1))
+        else
+            some_dict[$day]=1
+        fi
+    done < $FILE
+
+    for day in ${!some_dict[@]}; do echo ${some_dict[$day]} $day; done | sort -rn | head -10
+}
+```
+
+#### Common algorithms
+
+* Hamming distance
+
+```
+distance=0
+for i in $(seq 1 ${#1}); do
+  if [ ${1:$i-1:1} != ${2:$i-1:1} ]; then
+    distance=$((distance+1))
+  fi
+done
+echo $distance
+```
+
+#### Text Manipulation
+
+* Take the first letter of every word in a line: `echo $line | sed 's/\(.\)[^ ]* */\1/g'`

resources/kubernetes.md

@@ -19,7 +19,13 @@ Name | Comments
 :------ |:--------:
 [Kubernetes Networking](https://github.com/nleiva/kubernetes-networking-links) | Kubernetes Networking Resources
 [Liveness and Readiness Probes](https://www.openshift.com/blog/liveness-and-readiness-probes) |
-[Kubernetes Troubleshooting Visual Guide](https://learnk8s.io/troubleshooting-deployments?fbclid=IwAR2k6ziNfhBe--CKoYP6qh5_lHYM7_kruDjc1EcyrpgyV_tKJzQlwiuA_Jk) |
+
+### Kubernetes - Troubleshooting
+
+Name | Comments
+:------ |:--------:
+[troubleshoot.sh](https://troubleshoot.sh) | "A kubectl plugin providing diagnostic tools for Kubernetes applications"
+[Kubernetes Troubleshooting Visual Guide](https://learnk8s.io/troubleshooting-deployments) |
 
 ### Kubernetes - Security
 

resources/linux.md

@@ -107,6 +107,14 @@ sudo ausearch -m avc -m user_avc -m selinux_err -m user_selinux_err -i -ts today
 * Reset "document text" value: `gsettings reset org.gnome.desktop.interface document-font-name`
 * Reset "Legacy Window Titles": `gsettings reset org.gnome.desktop.wm.preferences titlebar-font`
 
+#### Files
+
+* Sort files by size: `ls -l | sort -nk5`
+
+#### Misc
+
+* Generate 8 digit random number: `shuf -i 9999999-99999999 -n 1`
+
 ## Checklist
 
 Check your Linux educational progress with the following list: