Sometime ago, somewhere on here, I said I was going to do some coding for Android.
I installed the full dev kit and a few months ago this MBP developed a failed HDD consequently destroying the dev environment.

I got an Android phone for XMAS and downloaded a terminal program.

I then found out how VERY limited the command line was/is.
I have no intention of rooting the phone at the moment as I want to see what I can create with the limited access available...
I also do not intend downloading a text editor - see the end of this upload...

Many things we take for granted are not available and there is very limited I/O;
printf, tr, sed, od, xxd, hexdump and many many other commands are not available.
This has set me on a quest to create some tools, albeit some might be slow, to aid is shell scripting.
(A basic DEMO hex dumper using echo is elsewhere on here but here are some more simpler other ones.)

1) ENVARC - Who remembers that then eh! <wink>
This is called as . ./ENVARC and adds the TMPDIR variable that does not exist in Android and extends the PATH to include another /some/path/to/Home/bin folder for executables.

Code:

#!/system/bin/sh
# ENVARC
PATH=$PATH:/storage/sdcard0/Home/bin
TMPDIR=/storage/sdcard0/Home/tmp

This can be called/sourced from the command line or inside any code you write...

2) reset - A terminal reset command that seems to reset the terminal and DOES clear the screen.

Code:

#!/system/bin/sh
# reset<CR>
echo -n -e "\x1Bc\x1B[0m\x1B[2J\x1B[H"
clear

3) d2u - A dos2unix workalike.

Code:

#!/system/bin/sh
# d2u <infile> [outfile]<CR>
. /storage/sdcard0/Home/bin/ENVARC
ifs_str="$IFS"
IFS=""
newfile=""
substring=0
outfile=$2
if [ "$1" == "" ]
then
	echo "Usage: d2u <infile> [outfile]..."
	exit 1
fi
if [ "$2" == "" ]
then
	outfile=$1
fi
read -s -d '' -r oldfile < $1
while [ $substring -lt ${#oldfile} ]
do
	if [ "${oldfile:$substring:1}" == $'\r' ]
	then
		substring=$((substring+1))
	else
		newfile=$newfile${oldfile:$substring:1} 
		substring=$((substring+1))
	fi
done
IFS="$ifs_str"
echo -n "$newfile" > $outfile
echo "File, $1, now converted to UNIX format..."
exit 0

And finally my editor running inside my new */bin folder, ( yes I do have Ctrl-C <wink>), cat > my_executable with Ctrl-C to exit...

A cleaned up version of the hex dumper is next then I am going to attempt a simple text editor as there are no editors either...

If there are better coding practices then I am completely open to them.

Bazza...