Help in explaining this echo conundrum. Post: 302993798

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Operating Systems OS X (Apple) Help in explaining this echo conundrum. Post 302993798 by wisecracker on Tuesday 14th of March 2017 01:41:35 PM

03-14-2017

Registered User

Help in explaining this echo conundrum.

OSX 10.12.3, default bash terminal.
Consider this code and note it is calling 'sh' inside the code...

Code:

#!/bin/sh
echo '1\n2\n2\n3\n5' > /tmp/text
hexdump -C /tmp/text
/bin/echo '1\n2\n3\n4\n5' > /tmp/text
hexdump -C /tmp/text

Now view the interactive mode below, note the underlying shell is bash:-

Code:

Last login: Tue Mar 14 17:12:45 on ttys001
AMIGA:barrywalker~> # Use sh first...
AMIGA:barrywalker~> sh
AMIGA:barrywalker~> cd Desktop/Code/Shell
AMIGA:barrywalker~/Desktop/Code/Shell> echo '1\n2\n3\n4\n5' > /tmp/text
AMIGA:barrywalker~/Desktop/Code/Shell> hexdump -C /tmp/text
00000000  31 0a 32 0a 33 0a 34 0a  35 0a                    |1.2.3.4.5.|
0000000a
AMIGA:barrywalker~/Desktop/Code/Shell> /bin/echo '1\n2\n3\n4\n5' > /tmp/text
AMIGA:barrywalker~/Desktop/Code/Shell> hexdump -C /tmp/text
00000000  31 5c 6e 32 5c 6e 33 5c  6e 34 5c 6e 35 0a        |1\n2\n3\n4\n5.|
0000000e
AMIGA:barrywalker~/Desktop/Code/Shell> ./echo_test.sh
00000000  31 0a 32 0a 32 0a 33 0a  35 0a                    |1.2.2.3.5.|
0000000a
00000000  31 5c 6e 32 5c 6e 33 5c  6e 34 5c 6e 35 0a        |1\n2\n3\n4\n5.|
0000000e
AMIGA:barrywalker~/Desktop/Code/Shell> # Now exit sh...
AMIGA:barrywalker~/Desktop/Code/Shell> exit
exit
AMIGA:barrywalker~> bash -version
GNU bash, version 3.2.57(1)-release (x86_64-apple-darwin16)
Copyright (C) 2007 Free Software Foundation, Inc.
AMIGA:barrywalker~> cd Desktop/Code/Shell
AMIGA:barrywalker~/Desktop/Code/Shell> echo '1\n2\n3\n4\n5' > /tmp/text
AMIGA:barrywalker~/Desktop/Code/Shell> hexdump -C /tmp/text
00000000  31 5c 6e 32 5c 6e 33 5c  6e 34 5c 6e 35 0a        |1\n2\n3\n4\n5.|
0000000e
AMIGA:barrywalker~/Desktop/Code/Shell> /bin/echo '1\n2\n3\n4\n5' > /tmp/text
AMIGA:barrywalker~/Desktop/Code/Shell> hexdump -C /tmp/text
00000000  31 5c 6e 32 5c 6e 33 5c  6e 34 5c 6e 35 0a        |1\n2\n3\n4\n5.|
0000000e
AMIGA:barrywalker~/Desktop/Code/Shell> ./echo_test.sh
00000000  31 0a 32 0a 32 0a 33 0a  35 0a                    |1.2.2.3.5.|
0000000a
00000000  31 5c 6e 32 5c 6e 33 5c  6e 34 5c 6e 35 0a        |1\n2\n3\n4\n5.|
0000000e
AMIGA:barrywalker~/Desktop/Code/Shell> _

1) Why does the 'bash' interactive mode give a different result to the 'sh' mode as 'sh' is merely a subset of 'bash'?
2) Why does echo in 'sh' translate '\n' to newlines in single quotes?
I thought single quotes were to give a raw string of characters, irrespective?
(Is this an Apple OSX thing?)
The 'sh' version is the same as the 'bash' version but are NOT identical files.

TIA...

wisecracker

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LEARN ABOUT SUNOS

jdshelp

jdshelp(1)							   User Commands							jdshelp(1)

NAME

       jdshelp - Java Desktop System Help browser

SYNOPSIS

       jdshelp [URL] [gnome-std-options]

DESCRIPTION

       jdshelp displays the Java Desktop System online Help.

       If a URL is specified, jdshelp displays the topic referenced by the URL. The URL must be a ghelp URL.

       If no argument is specified, jdshelp displays the complete online Help.

OPTIONS

       The following options are supported:

       gnome-std-optionStandard options available for use with most GNOME applications.  See gnome-std-options(5) for more information.

OPERANDS

       The following operands are supported:

       URL	       Uniform Resource Locator, the location of a Help topic.

EXAMPLES

       Example 1: Displaying the Text Editor Online Help

       example% jdshelp ghelp://usr/share/gnome/help/gedit/C/gedit.xml

EXIT STATUS

       The following exit values are returned:

       0	Application exited successfully

       >0	Application exited with failure

FILES

       The following files are used by this application:

       /usr/bin/jdshelp        Executable for Java Desktop System Help browser

ATTRIBUTES

       See attributes(5) for descriptions of the following attributes:

       +-----------------------------+-----------------------------+
       |      ATTRIBUTE TYPE	     |	    ATTRIBUTE VALUE	   |
       +-----------------------------+-----------------------------+
       |Availability		     |SUNWgnome-*		   |
       +-----------------------------+-----------------------------+
       |Interface stability	     |External			   |
       +-----------------------------+-----------------------------+

SEE ALSO

       Latest version of the GNOME Desktop User Guide for your platform.

       yelp(1)

NOTES

       Written by Laszlo Kovacs, Sun Microsystems Inc., 2004.

SunOS 5.10							    29 Oct 2004 							jdshelp(1)