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Full Discussion: the expr \*
Top Forums Shell Programming and Scripting the expr \* Post 302543195 by agama on Friday 29th of July 2011 10:29:04 PM
Old 07-29-2011
At first glance you might think that because the parameters to the echo are placed within double quotes that there'd be no expansion of the splat (*) in the expression command. However, the shell treats everything between backquotes as an independent string, and thus it's contents need to be further protected.

You should be able to code it this way if using a backslash bothers you:
Code:
echo "$n * $i = `expr $i '*' $n`"

Further info if you need it....
If the splat isn't escaped or quoted within the backtick string, the shell will expand the "wildcard" to be all files in the current working directory and the expression command will generate a syntax error.
Last edited by agama; 07-29-2011 at 11:33 PM.. Reason: further clarification at end
 

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LEARN ABOUT LINUX

shtool-echo

SHTOOL-ECHO.TMP(1)					      GNU Portable Shell Tool						SHTOOL-ECHO.TMP(1)

NAME

       shtool-echo - GNU shtool echo(1) extensional command

SYNOPSIS

       shtool echo [-n|--newline] [-e|--expand] string

DESCRIPTION

       shtool echo is an echo(1) style command which prints string to stdout and optionally provides special expansion constructs (terminal bold
       mode, environment details, date, etc) and newline control. The trick of this command is that it provides a portable -n option and hides the
       gory details needed to find out the environment details under option -e.

OPTIONS

       The following command line options are available.

       -n, --newline
	   By default, output is written to stdout followed by a "newline" (ASCII character 0x0a). If option -n is used, this newline character is
	   omitted.

       -e, --expand
	   If option -e is used, string can contain special "%x" constructs which are expanded before the output is written. Currently the
	   following constructs are recognized:

	   %B  switch terminal mode to bold display mode.

	   %b  switch terminal mode back to normal display mode.

	   %u  the current user name.

	   %U  the current user id (numerical).

	   %g  the current group name.

	   %G  the current group id (numerical).

	   %h  the current hostname (without any domain extension).

	   %d  the current domain name.

	   %D  the current day of the month.

	   %M  the current month (numerical).

	   %m  the current month name.

	   %Y  the current year.

EXAMPLE

	#   shell script
	shtool echo -n -e "Enter your name [%B%u%b]: "; read name
	shtool echo -e "Your Email address might be %u@%h%d"
	shtool echo -e "The current date is %D-%m-%Y"

HISTORY

       The GNU shtool echo command was originally written by Ralf S.  Engelschall <rse@engelschall.com> in 1998 for Website META Language (WML)
       under the name buildinfo. It was later taken over into GNU shtool.

SEE ALSO

       shtool(1), echo(1).

18-Jul-2008							   shtool 2.0.8 						SHTOOL-ECHO.TMP(1)
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