Unable To Install CS50 Library for C on Android Termux

Question

I downloaded cs50 library for C per the instructions on cs50 docs site.

I then unzip it and run sudo make install but it display the error below:

No superuser binary detected. Are you rooted?

I'm running Termux app on Android, and uses vim as editor.

How do I fix the above? If I decide to root my device will this be solve or is there a workaround to this without having to root my device? TIA.

Answer 1

1. Edit the Makefile

From

DESTDIR ?= /usr/local
MANDIR ?= share/man/man3

To

DESTDIR = /data/data/com.termux/files/usr/local
MANDIR = /data/data/com.termux/files/usr/share/man/man3

In the Makefile, the question mark equal sign (?=) is for asking if the variable isn't defined. In this case just force it to use the specified path.

2. Build & Install without SUDO

$ make install

You'll end up getting an error at end

ldconfig /data/data/com.termux/files/usr/local/lib
make: ldconfig: No such file or directory
make: *** [Makefile:55: install] Error 127

However the libraries are in the /data/data/com.termux/files/usr/local/lib directory and the man files should be in the right place

$ man get_string

should display the CS50 man page for get_string

3. Add missing linking reference

More of a hack but works, as ldconfig doesn't appear to be available in Termux.

In build/lib there should be three files:

$ ls -1
libcs50.a
libcs50.so
libcs50.so.10.1.10

These three same files should also be in: /data/data/com.termux/files/usr/local/lib

$ cd /data/data/com.termux/files/usr/local/lib
$ ls -l
.... libcs50.a
.... libcs50.so -> libcs50.so.10.1.0
.... libcs50.so.10.1.0

You'll need to add one symbolic link for libcs50.so.10:

$ ln -s libcs50.so.10.1.0 libcs50.so.10
$ ls -l
.... libcs50.a
.... libcs50.so -> libcs50.so.10.1.0
.... libcs50.so.10 -> libcs50.so.10.1.0
.... libcs50.so.10.1.0

4. Add needed environment variables

$ export LIBRARY_PATH="/data/data/com.termux/files/usr/local/lib"
$ export LD_LIBRARY_PATH="/data/data/com.termux/files/usr/local/lib"

You'll probably want to add these to your shell environment.

5. Run test C code

$ cd <unzip_directory>/tests

realize that the files in tests are using an older CS50 API so

in hackerrank.c needs to be changed from

string s = get_string();

to

string s = get_string("Type here:");

for it to compile correctly. Otherwise you'll get errors like

hackerrank.c:6:16: error: expected expression
string s = get_string();
^
/data/data/com.termux/files/usr/local/include/cs50.h:109:53: note:
expanded from macro 'get_string'
...get_string(NULL, __VA_ARGS__)
^
1 error generated.

So once the edit is made. Compile the code.

$ cc -lcs50 hackerrank.c
$ ./a.out
Type here: <type stuff>
hello, <type stuff output>
$

Always double check your environment variables with the export command if you are having problems compiling or running.

$ export
...
...
declare -x LIBRARY_PATH="/data/data/com.termux/files/usr/local/lib"
declare -x LD_LIBRARY_PATH="/data/data/com.termux/files/usr/local/lib"
...
...