#! /bin/bash

# script showing a "Hello world!"

echo "Hello world!"

$ chmod +x 01_hello_world.sh

$ ./01_hello_world.sh

ficheros_shell_scripts.sh
VARIABLES_DE_ENTORNO
variables_locales
nombres_de_funciones

#! /bin/bash

# Short description of the script

set -o errexit  # the script ends if a command fails
set -o pipefail # the script ends if a command fails in a pipe
set -o nounset  # the script ends if it uses an undeclared variable
# set -o xtrace # if you want to debug

#! /bin/bash

num_params=$#

if [[ $num_params -lt 1 ]]; then
    echo "At least one parameter must be introduced."
    exit 1 # error and exits with a return code > 0
fi

echo "All ok" # ok and exits with a return code = 0

date=$(date +'%Y-%m-%d %H:%M:%S')

my_function() {
  local function_param_1="$1"    # 1st param assigned as local
  global_param_2=${2:-default}   # 2nd param assigned as global (default)
  local function_num_params=$#   # numbers of params assigned as local
  local all_function_params=($@) # all params assigned as a local
}

my_function function_param_1 function_param_2 ... function_param_N

# Main function
main() {

  check "$@"
  params "$@"
  print
}

main "$@" # call the main function with all the parameters

# Default values
default_2="Commit Conf"

param_1=$1                 # the first script param
param_2=${2:-${default_2}} # the second script param (with default value)
num_params=$#              # the numbers of script params
all_params=($@)            # all params assigned as an array

$ ./02_parameters.sh param_1 param_2 ... param_N

awk 'awk_program' data_file

awk -f 'awk_file' data_file

Pepito      4.4  3.1  5.7
Fulanito    4.2  6.5  8.8
Menganito   5.6  5.0  5.3

awk '{ print $1"="($2+$3+$4)/3 }' 03_grades.csv

Pepito:Jefe,Sistemas
Fulanito:Jefe,Desarrollo
Menganito:Operario,Sistemas,Desarrollo

Sistemas -> Menganito Pepito 
Operario -> Menganito 
Jefe -> Fulanito Pepito 
Desarrollo -> Menganito Fulanito 

roles_file=./05_roles.csv

roles=$(cut -d : -f 2 $roles_file | sed 's/,/\n/g' | sort | uniq)

for rol in $roles; do
  echo -n "${rol} -> "
  echo $(grep -E "${rol}" "${roles_file}" | cut -d : -f 1)
done

# this will run only once at first
BEGIN { FS = ",|:" }
# this will be executed for each of the lines in the file
{
  name=$1
  for (i=2; i<=NF; i++) {
    roles[$i]=roles[$i]" "old_names
  }
}
# This will only run once at the end
END {
  for (rol in roles) {
    print rol" -> " roles[rol]
  }
}