Snippets

README.md

Snippets

Ejemplos en Linux Bash y otros lenguajes

Leer una entrada

echo -n "Proceed? [y/n]: "
read -r ans
echo "$ans"

Condicionales

if ping -c 1 google.com; then
  echo "It appears you have a working internet connection"
fi

if grep -q 'ping' ~/.bash_history; then
  echo "Tu escribiste 'ping' alguna vez."
fi

while [[ "$1" =~ ^- && ! "$1" == "--" ]]; do case $1 in
  -V | --version )
    echo "$version"
    exit
    ;;
  -s | --string )
    shift; string=$1
    ;;
  -f | --flag )
    flag=1
    ;;
esac; shift; done
if [[ "$1" == '--' ]]; then shift; fi

Case switch

case "$1" in
  start | up)
    vagrant up
    ;;

  *)
    echo "Usage: $0 {start|stop|ssh}"
    ;;
esac

Realizar operaciones

$((a + 200))      # Add 200 to $a

$(($RANDOM%200))  # Random number 0..199

declare -i count  # Declare as type integer 
count+=1          # Increment

# String
if [[ -z "$string" ]]; then
  echo "String is empty"
elif [[ -n "$string" ]]; then
  echo "String is not empty"
else
  echo "This never happens"
fi

# Combinations
if [[ X && Y ]]; then
  ...
fi

# Equal
if [[ "$A" == "$B" ]]

# Regex
if [[ "A" =~ . ]]

if (( $a < $b )); then
   echo "$a is smaller than $b"
fi

if [[ -e "file.txt" ]]; then
  echo "file exists"
fi

Parámetro	Significado
$?	Exit status of last task
$!	PID of last background task
$$	PID of shell
$0	Filename of the shell script
$_	Last argument of the previous command
${PIPESTATUS[n]}	return value of piped commands (array)

Instruccón	Significado
[[ -e FILE ]]	Exists
[[ -r FILE ]]	Readable
[[ -h FILE ]]	Symlink
[[ -d FILE ]]	Directory
[[ -w FILE ]]	Writable
[[ -s FILE ]]	Size is > 0 bytes
[[ -f FILE ]]	File
[[ -x FILE ]]	Executable
[[ FILE1 -nt FILE2 ]]	1 is more recent than 2
[[ FILE1 -ot FILE2 ]]	2 is more recent than 1
[[ FILE1 -ef FILE2 ]]	Same files
[[ -o noclobber ]]	If OPTIONNAME is enabled
[[ ! EXPR ]]	Not
[[ X && Y ]]	And
[[ X or Y ]]	Or
[[ -z STRING ]]	Empty string
[[ -n STRING ]]	Not empty string
[[ STRING == STRING ]]	Equal
[[ STRING != STRING ]]	Not Equal
[[ NUM -eq NUM ]]	Equal
[[ NUM -ne NUM ]]	Not equal
[[ NUM -lt NUM ]]	Less than
[[ NUM -le NUM ]]	Less than or equal
[[ NUM -gt NUM ]]	Greater than
[[ NUM -ge NUM ]]	Greater than or equal
[[ STRING =~ STRING ]]	Regexp
(( NUM < NUM ))	Numeric conditions

Enlaces:

• https://devhints.io/bash
• https://htmlcheatsheet.com/js/
• https://cheatography.com/itsellej/cheat-sheets/git-commands/
• https://quickref.me/python
• https://dockerlabs.collabnix.com/docker/cheatsheet/
• https://devhints.io/vue
• https://upmostly.com/ultimate-reactjs-cheat-sheet

guardar.js

//el archivo JSON lo convierto a un array y lo guardo en la variable series
var series;

//funcion que lee mi archivo JSON
function loadData(){
    let data = JSON.parse(fs.readFileSync(path.resolve('data','series.json'),'utf8' ,(err,data) => {
        if (err){console.error(err); return;}
        return data;
    }));
    series = data.series;
}

//Cuando guardo los cambios se dispara la función save que recibe como párametro el id
//de la serie
function save(index) {
    //Modifico los datos directamente en el array
    series[index] = {
        titulo: `${document.getElementById('titulo').value}`,
        descripcion: `${document.getElementById('descripcion').value}`,
        fecha_emision: `${document.getElementById('fecha_emision').value}`,
        imagen: `${document.getElementById('imagen').getAttribute('src')}`
    };
    
    //creo una variable con un objeto que tiene la estructura del archvo JSON
    let jsonData = {series : series};

    //con la clase fs sobreescribo el archivo ya con los cambios hechos
    fs.writeFileSync(path.resolve('data','series.json'), JSON.stringify(jsonData), (err) => {
        if (err) throw err;
    });
    //metodo para cerrar un modal en materialize css
    instances.close();
    //mando llamar mi fucnion load que es la que vuelve a llenar mis variables globales
    //como la variable series
    loadData();
}