linux.md

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page	Termux and Linux

The environment setup in Termux is similar to that of a modern Linux distribution. However, running on Android implies several important differences:

• Common folders such as /bin, /usr/, /var and /etc does not exist.
• The Android system provides a basic non-standard file system hierarchy, where e.g. /system/bin contains some system binaries.
• The user folder $HOME is inside the private file area exposed to Termux as an ordinary Android app. Uninstalling Termux will cause this file area to be wiped - so save important files outside this area such as in /sdcard or use a version control system such as git.
• Termux installs its packages in a folder exposed through the $PREFIX environment variable (with e.g. binaries in $PREFIX/bin, and configuration in $PREFIX/etc).
• The normal #!/usr/bin/... she-bangs will not work. Use the termux-fix-shebang script to modify these files before executing.
• Shared libraries are installed in $PREFIX/lib, which are available from binaries due to Termux setting the $LD_LIBRARY_PATH environment variable. These may clash with Android system binaries in /system/bin, which may force LD_LIBRARY_PATH to be cleared before running system binaries.
• Besides the file system being different, Termux is running as a single-user system without root - each Android app is running as its own Linux user, so running commands inside Termux may not interfere with other installed applications.

Running as non-root implies that ports below 1024 cannot be bound to. Many packages have been configured to have compatible default values - the ftpd, httpd, and sshd servers default to 8021, 8080 and 8022, respectively.