Referencias indirectas

usar el valor de una variable para acceder al contenido de otra

# declaramos 2 variables
export xyzzy=plugh ; export plugh=cave
 
echo ${xyzzy}  # normal, xyzzy to plugh -> plugh
 
echo ${!xyzzy} # indirection, xyzzy to plugh to cave -> cave

existen 2 casos en el que este comportamiento se ve modificado:

• ${!N*} : muestra las variables que empiecen por N
• ${!name[@]}

export myVar="hi"
echo ${!my*} # myVar
 
export ${!my*}="bye"
echo $myVar # bye

/vía: https://stackoverflow.com/questions/8515411/what-is-indirect-expansion-what-does-var-mean

#!/bin/bash
 
AQUI_VALOR="GHJGHJGHJ"
VARIABLE=AQUI_VALOR
 
read -p "Valor: " VALOR
echo ${VALOR}
 
declare "${VARIABLE}=$VALOR"
# typeset equivalente a declare, soportado por otros shells (zsh)
# printf -v "${VARIABLE} '%s' "${VALOR}"
 
echo $AQUI_VALOR        # $VALOR
echo "=="
echo $VARIABLE          # $VARIABLE

/via: https://stackoverflow.com/questions/9938649/indirect-variable-assignment-in-bash

• http://tldp.org/LDP/abs/html/ivr.html
• https://stackoverflow.com/questions/8515411/what-is-indirect-expansion-what-does-var-mean
• en arrays: https://stackoverflow.com/questions/11180714/how-to-iterate-over-an-array-using-indirect-reference