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Top Forums Shell Programming and Scripting I need to understand the differences between the bash shell and the Bourne shell Post 302368272 by methyl on Wednesday 4th of November 2009 12:47:09 PM
Old 11-04-2009
Further to pludi.

The shebang line must be exactly as in pludi's post. The line is only needed if your default shell is not bash and you want to use bash though many use it to make it clear to others how to read the script. (On modern HP-UX the default shell /usr/bin/sh is actually a POSIX shell and there is no bash).
Code:
#!/bin/bash

Any extra characters after the above string are passed to the shell as one parameter signifying a filename for the shell to execute - whether or not a hash character is present. A hash character is valid in a filename.
Therfore this lines is invalid and will cause error messages.
Code:
#!/bin/bash # I think this command is BS > debug effort

 

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RBASH(1)						      General Commands Manual							  RBASH(1)

NAME
rbash - restricted bash, see bash(1) RESTRICTED SHELL
If bash is started with the name rbash, or the -r option is supplied at invocation, the shell becomes restricted. A restricted shell is used to set up an environment more controlled than the standard shell. It behaves identically to bash with the exception that the follow- ing are disallowed or not performed: o changing directories with cd o setting or unsetting the values of SHELL, PATH, ENV, or BASH_ENV o specifying command names containing / o specifying a file name containing a / as an argument to the . builtin command o specifying a filename containing a slash as an argument to the -p option to the hash builtin command o importing function definitions from the shell environment at startup o parsing the value of SHELLOPTS from the shell environment at startup o redirecting output using the >, >|, <>, >&, &>, and >> redirection operators o using the exec builtin command to replace the shell with another command o adding or deleting builtin commands with the -f and -d options to the enable builtin command o using the enable builtin command to enable disabled shell builtins o specifying the -p option to the command builtin command o turning off restricted mode with set +r or set +o restricted. These restrictions are enforced after any startup files are read. When a command that is found to be a shell script is executed, rbash turns off any restrictions in the shell spawned to execute the script. SEE ALSO
bash(1) GNU Bash-4.0 2004 Apr 20 RBASH(1)
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