A Bash script is basically a text file containing commands written in Bash command language. The script below for example will greet the name that we supply as a parameter:
#!/bin/bash echo Hello, $1!
The shell script can be executed as the following:
$ bash hello.sh Alice Hello, Alice!
File type details of the script can be viewed using the file command:
$ file hello.sh hello.sh: Bourne-Again shell script, ASCII text executable
Some of the caveats of using such script is that the code is clearly visible and it might not be as performant as running a compiled program.
shc is a Bash script compiler and you can use it to hide the source code (as some would say “encrypt”) of the Bash script and remove dependency to Bash interpreter by compiling your Bash script into an executable binary from the command line.
$ sudo apt update && sudo apt install --assume-yes gcc shc #For //Ubuntu// / //Debian//. ##### snipped The following additional packages will be installed: binutils binutils-common binutils-x86-64-linux-gnu cpp cpp-8 gcc-8 libasan5 libatomic1 libbinutils libc-dev-bin libc6-dev libcc1-0 libgcc-8-dev libgomp1 libisl19 libitm1 liblsan0 libmpc3 libmpx2 libquadmath0 libtsan0 libubsan1 linux-libc-dev manpages-dev Suggested packages: binutils-doc cpp-doc gcc-8-locales gcc-multilib make autoconf automake libtool flex bison gdb gcc-doc gcc-8-multilib gcc-8-doc libgcc1-dbg libgomp1-dbg libitm1-dbg libatomic1-dbg libasan5-dbg liblsan0-dbg libtsan0-dbg libubsan1-dbg libmpx2-dbg libquadmath0-dbg glibc-doc The following NEW packages will be installed: binutils binutils-common binutils-x86-64-linux-gnu cpp cpp-8 gcc gcc-8 libasan5 libatomic1 libbinutils libc-dev-bin libc6-dev libcc1-0 libgcc-8-dev libgomp1 libisl19 libitm1 liblsan0 libmpc3 libmpx2 libquadmath0 libtsan0 libubsan1 linux-libc-dev manpages-dev shc 0 upgraded, 26 newly installed, 0 to remove and 0 not upgraded. Need to get 27.8 MB of archives. ##### snipped
For other Linux distributions.
$ shc -f hello.sh
$ ls -l hello* -rw-rw-r-- 1 user user 29 Mar 14 07:37 hello.sh -rwxrwxr-x 1 user user 14960 Mar 14 07:39 hello.sh.x -rw-rw-r-- 1 user user 10047 Mar 14 07:39 hello.sh.x.c
.sh is the original script.
sh.x is the compiled binary.
.sh.x.c is the C source code generated from the .sh file prior to compiling to .sh.x.
hello.sh.x permission is automatically set as executable
$ file hello.sh.x hello.sh.x: ELF 64-bit LSB shared object, x86-64, version 1 (SYSV), dynamically linked, interpreter /lib64/ld-linux-x86-64.so.2, for GNU/Linux 3.2.0, BuildID[sha1]=22ba5ae2974d014bc0336e5888d076c82c697d64, stripped
$ mv hello.sh.x hello
$ ./hello Alice Hello, Alice!
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