How to compile a Bash script to a binary

Compiling a Bash script with shc creates an executable wrapper that hides the plain script body and can be distributed like another local binary. Operators can keep a command-style entry point such as hello instead of shipping a readable .sh file.

shc reads the script named with -f, writes generated C source to a .x.c file, and uses the system C compiler to build the executable. The compiled file still depends on the shell named in the script shebang and on normal system libraries, so it is not a static or fully independent program.

Use a direct shebang such as #!/bin/bash before compiling. If shc reports Unknown shell (env) for #!/usr/bin/env bash, switch to a direct shell path or supply the explicit -i, -x, and -l options before relying on the generated binary.

1. Refresh the APT package index on Ubuntu or Debian.

   $ sudo apt update

2. Install shc and GCC.

   $ sudo apt install --assume-yes gcc shc
   Reading package lists... Done
   Building dependency tree... Done
   The following NEW packages will be installed:
     gcc shc
   ##### snipped #####
   Setting up shc (4.0.3-1ubuntu2) ...
   Setting up gcc (4:15.2.0-5ubuntu1) ...

3. Confirm that the script starts with a direct Bash shebang.

   hello.sh

   #!/bin/bash
   name=${1:-world}
   printf 'Hello, %s!\n' "$name"

   shc can compile other shell scripts when the matching -i, -x, and -l options are supplied. For a normal Bash script, a direct #!/bin/bash shebang keeps the default compile step simple.

4. Compile the script with shc and name the output binary hello.

   $ shc -f hello.sh -o hello

5. List the generated files.

   $ ls -l hello hello.sh hello.sh.x.c
   -rwxrwxr-x 1 user user 68264 Jun  5 02:10 hello
   -rwxr-xr-x 1 user user    59 Jun  5 02:10 hello.sh
   -rw-r--r-- 1 user user 17891 Jun  5 02:10 hello.sh.x.c

   The hello file is the executable wrapper. The hello.sh.x.c file is generated C source used to build that wrapper.

6. Check that the generated executable is an ELF binary.

   $ file hello
   hello: ELF 64-bit LSB pie executable, ARM aarch64, version 1 (SYSV), dynamically linked, interpreter /lib/ld-linux-aarch64.so.1, BuildID[sha1]=98f5f6c5e7a9ea25f44e77a48edd2f38a64cfeb6, for GNU/Linux 3.7.0, stripped

   The architecture in the output matches the system where shc and GCC built the binary.

7. Run the generated executable with the same arguments as the original script.

   $ ./hello Bob
   Hello, Bob!

8. Check the runtime library dependencies before distributing the binary to another system.

   $ ldd hello
   	linux-vdso.so.1 (0x0000ffff939cc000)
   	libc.so.6 => /usr/lib/aarch64-linux-gnu/libc.so.6 (0x0000ffff93790000)
   	/lib/ld-linux-aarch64.so.1 (0x0000ffff93990000)

   ldd shows system libraries, but shc also needs the shell named by the script shebang when the binary runs.