ajout qq sources dans readme

README.md

@@ -152,8 +152,13 @@ two more functions :
 - [process substitution](https://www.linuxjournal.com/content/shell-process-redirection)
 - [read, IFS](https://unix.stackexchange.com/questions/164508/why-do-newline-characters-get-lost-when-using-command-substitution)
 - [process substitution](https://www.gnu.org/software/bash/manual/bash.html#Process-Substitution)
+- [variable substitution](https://www.gnu.org/software/bash/manual/html_node/Shell-Parameter-Expansion.html)
 - [send one command to two pipes](https://stackoverflow.com/questions/13107783/pipe-output-to-two-different-commands)
 - [send two commands to one pipe](https://askubuntu.com/questions/133386/how-to-merge-and-pipe-results-from-two-different-commands-to-single-command)
 - ["\[" vs "\[\[" in bash](https://stackoverflow.com/questions/13542832/difference-between-single-and-double-square-brackets-in-bash)
 - [redirections in bash](https://stackoverflow.com/questions/818255/in-the-shell-what-does-21-mean)
 - [bash variable of variable](https://stackoverflow.com/questions/10757380/bash-variable-variables)
+- [bash fork &](https://unix.stackexchange.com/questions/7608/does-bash-support-forking-similar-to-cs-fork/7609#7609)
+- [read a var line by line](https://unix.stackexchange.com/questions/9784/how-can-i-read-line-by-line-from-a-variable-in-bash)
+- [wait for not-a-child process to finish](https://stackoverflow.com/questions/1058047/wait-for-a-process-to-finish)
+