[Bug]: Have /usr/bin/env

[superbonaci]

Problem description

Command /usr/bin/env is missing, it's only /bin/env. All operating systems expect env to be in in /usr/bin/env:

https://www.cyberciti.biz/tips/finding-bash-perl-python-portably-using-env.html https://www.diskinternals.com/linux-reader/usr-bin-bash/

Steps to reproduce the behavior.

Try to locate /usr/bin/env

What is the expected behavior?

Have env in location

System information

• Termux application version: 0.118.1
• Android OS version:
• Device model:

[twaik]

https://wiki.termux.com/wiki/Differences_from_Linux

[TomJo2000]

#!/usr/bin/env shebangs are already supported through termux-exec's shebang fix mechanism.

Since Android does not permit regular applications to write to system directories we need to translate interpreter directives (shebangs) anyway. As such #!/usr/bin/env becomes #!/data/data/com.termux/files/usr/bin/env

[superbonaci]

But do I need to manually run termux-exec or is already being taken care of with default installation?

[TomJo2000]

It is a core termux utility and should be part of the default installation.

[superbonaci]

Not installed:

~ $ termux-exec
No command termux-exec found, did you mean:
 Command termux-nfc in package termux-api
 Command termux-open in package termux-tools
 Command termux-x11 in package termux-x11-nightly from the x11-repo repository

[twaik]

It is not a command.

[TomJo2000]

It's a library, not a command. https://github.com/termux/termux-exec

[superbonaci]

But I have it installed, how is it supposed to work, can I use regular scripts with the shebang #!/usr/bin/env?

~ $ pkg install termux-exec
Checking availability of current mirror:
[*] https://mirrors.de.sahilister.net/termux/termux-main: ok
Reading package lists... Done
Building dependency tree... Done
Reading state information... Done
termux-exec is already the newest version (1:1.0).
The following packages were automatically installed and are no longer required:
  binutils binutils-bin binutils-libs gettext
  gnutls googletest libcroco libice libsm
  libtasn1 libxcursor libxfixes libxrandr
  libxt p11-kit unbound xorg-util-macros
  xorgproto
Use 'apt autoremove' to remove them.
0 upgraded, 0 newly installed, 0 to remove and 0 not upgraded.

[TomJo2000]

Dark syscall interception magic. Honestly beyond me, but the whole program is only 238 lines of C.

[agnostic-apollo]

What is your android version?

[superbonaci]

I'm testing it in Android 12. The shebang #!/usr/bin/env works when inside the script, however is not found directly, is that ok?:

#!/usr/bin/env bash
echo "abc"

~ $ ./run_check.sh
abc

~ $ type -a /usr/bin/env
bash: type: /usr/bin/env: not found

[TomJo2000]

I'm testing it in Android 12. The shebang #!/usr/bin/env works when inside the script, however is not found directly, is that ok?:

Well no. It wouldn't be. That's why we have the execve() shim. env is at /data/data/com.termux/files/usr/bin/env If you want that is a more Shell variable-ish way, it's at $PREFIX/bin/env, which is listed in the $PATH variable, thus your shell knows to search that directory for executables when trying to run a command from the command-line.

termux-exec modifies the shebang at call-time so that "off the shelf" scripts can work on Termux. Since a shebang does not perform a $PATH search (The main reason for using a #!/usr/bin/env shebang is that env command_name does that $PATH search)

[superbonaci]

The PATH in my Termux is only one directory:

~ $ echo $PATH
/data/data/com.termux/files/usr/bin

[TomJo2000]

Yes, since we don't get any of the standard UNIX-like utilities handed to us from Android in any useful or consistent way.

[agnostic-apollo]

The /usr/bin directory and /usr/bin/env file does not exist on Android, that's why you won't find its info. Only when you execute a file with a path or its in shebang, the /usr/bin and /bin prefixes are replaced with /data/data/com.termux/files/usr/bin.

Note that /bin is a symlink to /system/bin and /bin/env does exist on Android, but that is the one provided by Android itself with toybox, not by Termux, at /system/bin/env.

Do not try to check existence or type of /usr/bin/* files, that will fail.

Check https://github.com/termux/termux-exec/blob/bb75f48d646aa0478527196f1878df53cd1a257c/site/pages/en/projects/docs/technical/index.md#linux-vs-termux-bin-paths for more info.