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Full Discussion: I need to understand the differences between the bash shell and the Bourne shell
Top Forums Shell Programming and Scripting I need to understand the differences between the bash shell and the Bourne shell Post 302368471 by pludi on Thursday 5th of November 2009 01:29:25 AM
Old 11-05-2009
Microsoft, since the early days of DOS, uses the two bytes carriage-return/linefeed as end-of-line terminators (and ^Z instead of ^D for EOF). So this isn't a Windows 7 specialty. But when copy-and-pasting lines, the command prompt isn't sent that 2 byte sequence, but an emulation of the enter key, where it's up to the program to handle that correctly. Cygwin comes with both vim and emacs (and a multitude of other editors) that let you save files in UNIX format.

You can leave out the shebang line if you really only use the bash shell. But expect your script to fail as soon as someone tries to run it in another shell (ksh/csh/ash/dash/...). By default, the script is executed using the same shell the user is currently running, but with the shebang line you'll tell the system explicitly which shell to use. This is especially useful if you use different scripting languages:
  • You can write stand-alone awk programs using
    Code:
    #!/usr/bin/awk -f

  • Perl programs will almost guaranteed fail if you run them without stating the interpreter somewhere
The same is true for expect, TCL, Python, Ruby, ....

The standard output for bash (just like any other POSIX shell) is stdout. If that is connected to a terminal, output goes there. If it's connected to a file, likewise. Maybe it's just that your awk statement didn't match, and so didn't print anything.
 

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LEARN ABOUT OSF1

sh

sh(1)							      General Commands Manual							     sh(1)

NAME

       sh - Shell, the standard command language interpreter

DESCRIPTION

       [Tru64  UNIX]  Tru64  UNIX  provides two command interpreters with the name sh.	The XCU5.0 and POSIX.2 compliant command interpreter sh is
       available in the file /usr/bin/posix/sh and is described in the sh(1p) reference page.  The Bourne shell,  historically	known  as  sh,	is
       available in the file /usr/bin/sh and is described in the sh(1b) reference page.

       [Tru64 UNIX]  Your initial, or login, shell is determined by your entry in the file /etc/passwd. This file can be changed only by your sys-
       tem administrator. You must use whatever procedures are in place at your location to have this entry changed.

       [Tru64 UNIX]  If available on your system, you may use the passwd -s or the chsh commands to change your login shell.

									  Note

       This option is not available if your site manages passwords through the Network Information Service (NIS) facility.  Check with your system
       administrator.

       [Tru64 UNIX]  Subsequent shells spawned from the initial shell depend on the value in the environment variable BIN_SH.  If this variable is
       set to xpg4, the POSIX shell is started. If this variable is set to svr4, an SVR4 compliant version of the shell is started. If this  vari-
       able  is  unset,  the  Bourne shell is started. If this variable is set to any other value, an error is reported and the results are unpre-
       dictable. See the EXAMPLES section for information on setting this variable.

NOTES

       [Tru64 UNIX]  With Tru64 UNIX Version 4.0 the Korn shell, /usr/bin/ksh is the same as the POSIX shell /usr/bin/posix/sh.

RESTRICTIONS

       [Tru64 UNIX]  The file /etc/shells must include entries for both the POSIX shell /usr/bin/posix/sh and the Bourne  shell,  /usr/bin/sh.	If
       this file is incorrect, see your system administrator.

EXAMPLES

       Using  the  Bourne,  Korn,  or  POSIX  shell, to set the variable BIN_SH to use the POSIX/ XCU5.0compliant shell, enter: BIN_SH=xpg4 export
       BIN_SH Using the Bourne, Korn, or POSIX shell, to set the variable BIN_SH to use the SVR4 compliant shell, enter: BIN_SH=svr4 export BIN_SH
       Using the Bourne, Korn, or POSIX shell, to unset the variable BIN_SH, enter: unset BIN_SH Using the C/ shell, to set the variable BIN_SH to
       use the POSIX/XCU5.0 compliant shell, enter: setenv BIN_SH xpg4 Using the C/ shell, to set the variable BIN_SH to use  the  SVR4  compliant
       shell, enter: setenv BIN_SH svr4 Using the C/ shell, to unset the variable BIN_SH, enter: unsetenv BIN_SH

FILES

       User profile.  Contains user information, including the login shell name.  Contains the names of available and permitted shells.

SEE ALSO

       Commands:  csh(1), ksh(1), Bourne shell sh(1b), POSIX shell sh(1p), passwd(1)

       Files:  passwd(4), shells(4)

       Standards:  standards(5)

																	     sh(1)
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