So it uses the value of $n as a command. (It's the same as echo `$n` with backticks.)
Contrast:
See? Now if you assign n=2 it will echo the value of $2, etc. So you can change the name of the variable you are referring to programmatically, dynamically.
This is an advanced topic; if you don't have a use for it, don't bother. If you really want to understand this, I suggest you play around with set -x and try different things until you understand what's going on.
Hi, experts.
Whould anybody clear explay me difference and usage of these 3 commands (particulary in bash) :
exec
eval
source
I've tryed to read the manual pages but did not get much.
Also could not get something useful from Google search - just so much and so not exactly, that is... (3 Replies)
In POSIX shell, we don't have arrays, but we can iterate over a list like this:
#!/bin/sh
list="Fred Barney Wilma Betty"
for i in $list; do echo $i; done
Fred
Barney
Wilma
Betty
But let's say we want "Mr. Slate" in the list.
We know we can't just stick him in there like this:... (5 Replies)
Hi
How to call a shell scripting through a Perl scripting? Actually I need some value from Shell scripting and passes in the Perl scripting. So how can i do this? (2 Replies)
I am stuck on something that should really be simple, and was looking for some help..
I am new to shell scripting.Need help on this.....
The script is to find the stale nfs.
cat file
- - - - /abcd/1234
I am writing the script to check the nfs errors of above file
... (3 Replies)
According to the POSIX specifications eval is a special shell built-in, which should imply that variable assignments specified together with it should remain in effect after the built-in completes. Thus one would expect IFS to be changed after this:
var=$'a\nb c'
$ IFS=$'\n' eval '
for i in... (4 Replies)
Gents,
I have been working in a Solaris/Unix environment for about 9 months. I took some linux classses online before getting the job. But, I am not very good at scripting. I want to learn how to script. Do you think that I should start with Shell scripting or Perl? I wanted to continue with... (2 Replies)
Hi all,
some small script with eval turned me to crazy.
my OS is linux
Linux s10-1310 2.6.16.53-0.8.PTF.434477.3.TDC.0-smp #1 SMP Fri Aug 31 06:07:27 PDT 2007 x86_64 x86_64 x86_64 GNU/Linux
below script works well
#!/bin/bash
eval ssh remotehost date
eval ssh remotehost ls
below... (1 Reply)
anyone has any info on why this is complaining???
vivek@vivek-c5e55ef2e ~/TAC
$ zoneCounter=1
vivek@vivek-c5e55ef2e ~/TAC
$ optUsage1=23%
vivek@vivek-c5e55ef2e ~/TAC
$ eval eval echo "<th>Zone $zoneCounter </th><th align=\"left\"> \$optUsage$zoneCounter </th>"
-bash: syntax error... (13 Replies)
Discussion started by: vivek d r
13 Replies
LEARN ABOUT SUNOS
echo
echo(1B) SunOS/BSD Compatibility Package Commands echo(1B)NAME
echo - echo arguments to standard output
SYNOPSIS
/usr/ucb/echo [-n] [argument]
DESCRIPTION
echo writes its arguments, separated by BLANKs and terminated by a NEWLINE, to the standard output.
echo is useful for producing diagnostics in command files and for sending known data into a pipe, and for displaying the contents of envi-
ronment variables.
For example, you can use echo to determine how many subdirectories below the root directory (/) is your current directory, as follows:
o echo your current-working-directory's full pathname
o pipe the output through tr to translate the path's embedded slash-characters into space-characters
o pipe that output through wc -w for a count of the names in your path.
example% /usr/bin/echo "echo $PWD | tr '/' ' ' | wc -w"
See tr(1) and wc(1) for their functionality.
The shells csh(1), ksh(1), and sh(1), each have an echo built-in command, which, by default, will have precedence, and will be invoked if
the user calls echo without a full pathname. /usr/ucb/echo and csh's echo() have an -n option, but do not understand back-slashed escape
characters. sh's echo(), ksh's echo(), and /usr/bin/echo, on the other hand, understand the black-slashed escape characters, and ksh's
echo() also understands a as the audible bell character; however, these commands do not have an -n option.
OPTIONS -n Do not add the NEWLINE to the output.
ATTRIBUTES
See attributes(5) for descriptions of the following attributes:
+-----------------------------+-----------------------------+
| ATTRIBUTE TYPE | ATTRIBUTE VALUE |
+-----------------------------+-----------------------------+
|Availability |SUNWscpu |
+-----------------------------+-----------------------------+
SEE ALSO csh(1), echo(1), ksh(1), sh(1), tr(1), wc(1), attributes(5)NOTES
The -n option is a transition aid for BSD applications, and may not be supported in future releases.
SunOS 5.10 3 Aug 1994 echo(1B)