Log in to your system and type
echo $SHELL
at the prompt. You will see a response containing sh, csh, ksh or b ash.
You need to find out where bash is on your system, i.e., in which directory it’s installed. You might be able to find the location by typing "whereis" bash(especially if you are using the C shell); if that doesn‘t work, try whence bash , wich bash, or this complex command:*
whereis bash || whence bash || which bash
#
grep bash /etc/passwd | awk -F: ‘{print $7}‘ | sort -u
#h, which bash, or this
complex command: *
Learning_the_bash_Shell_Third_Edition 1/n
原文：https://www.cnblogs.com/winditsway/p/14240416.html