Added post_install.sh and post_remove.sh scripts

pkg.info

@@ -4,4 +4,5 @@ version: 5.2.21
 url: https://www.gnu.org/software/bash/
 license: GPL3-or-later
 architecture: any
+keep: etc/bashrc,etc/profile
 type: source

post_install.sh

@@ -0,0 +1,7 @@
+#!/bin/bash
+
+SHELL="/bin/bash"
+
+if ! grep "${SHELL}" "$BPM_ROOT"/etc/shells; then
+  echo "${SHELL}" | tee -a "$BPM_ROOT"/etc/shells
+fi

post_remove.sh

@@ -0,0 +1,7 @@
+#!/bin/bash
+
+SHELL="/bin/bash"
+
+if grep "${SHELL}" "$BPM_ROOT"/etc/shells; then
+  sed -i "s|${SHELL}|d" "$BPM_ROOT"/etc/shells
+fi