termux-packages/packages/proot/termux-chroot

#!/bin/sh

if [ $# != 0 ]; then
	echo "termux-chroot: Setup a chroot to mimic a normal Linux file system"
	echo ""
	echo "Execute without arguments to run a chroot with traditional file system"
	echo "hierarchy (having e.g. the folders /bin, /etc and /usr) within Termux."
	exit
fi

# For the /system/bin/linker(64) to be found:
ARGS="-b /system:/system"

# On some devices /vendor is required for termux packages to work correctly
# See https://github.com/termux/proot/issues/2#issuecomment-303995382
ARGS="$ARGS -b /vendor:/vendor"

# Bind $PREFIX so Termux programs expecting
# to find e.g. configurations files there work.
ARGS="$ARGS -b $PREFIX/..:$PREFIX/.."

# Expose external and internal storage:
if [ -d /storage ]; then
	ARGS="$ARGS -b /storage:/storage"
fi

# Mimic traditional Linux file system hierarchy - /usr:
ARGS="$ARGS -b $PREFIX:/usr"

# Mimic traditional Linux file system hierarchy - other Termux dirs:
for f in bin etc lib share tmp var; do
	ARGS="$ARGS -b $PREFIX/$f:/$f"
done

# Mimic traditional Linux file system hierarchy- system dirs:
for f in dev proc; do
	ARGS="$ARGS -b /$f:/$f"
done

# Set /home as current directory:
ARGS="$ARGS --cwd=/home"

# Root of the file system:
ARGS="$ARGS -r $PREFIX/.."

# Program to execute:
PROGRAM=/bin/bash
if [ -x $HOME/.termux/shell ]; then
	PROGRAM=`readlink -f $HOME/.termux/shell`
fi
ARGS="$ARGS $PROGRAM -l"

export HOME=/home
$PREFIX/bin/proot $ARGS