Sponsored Content
Full Discussion: eval in shell scripting
Top Forums Shell Programming and Scripting eval in shell scripting Post 302197554 by era on Wednesday 21st of May 2008 07:13:43 AM
Old 05-21-2008
eval is useful when cmd contains something which needs to be evaluated by the shell. The typical case would be when you have a variable containing the index of an argument you want to access.

Code:
n=1  # or whatever, just to make this self-contained
eval echo \${$n}

Search these forums for examples; some of them are rather elaborate.
 

10 More Discussions You Might Find Interesting

1. Shell Programming and Scripting

difference between AIX shell scripting and Unix shell scripting.

please give the difference between AIX shell scripting and Unix shell scripting. (2 Replies)
Discussion started by: haroonec
2 Replies

2. Shell Programming and Scripting

bash shell: 'exec', 'eval', 'source' - looking for help to understand

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)
Discussion started by: alex_5161
3 Replies

3. Shell Programming and Scripting

shell - word splitting - using eval

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)
Discussion started by: mjd_tech
5 Replies

4. Shell Programming and Scripting

Call Shell scripting from Perl Scripting.

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)
Discussion started by: anupdas
2 Replies

5. Shell Programming and Scripting

eval in shell scripting

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)
Discussion started by: nareshkumar522
3 Replies

6. UNIX for Advanced & Expert Users

Variable assignments specified with eval shell built-in

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)
Discussion started by: Scrutinizer
4 Replies

7. What is on Your Mind?

Shell Scripting vs Perl scripting

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)
Discussion started by: Pouchie1
2 Replies

8. Shell Programming and Scripting

Strange result of eval, how does eval really work with ssh?

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)
Discussion started by: summer_cherry
1 Replies

9. Shell Programming and Scripting

Error in eval eval command to print html tags

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... (1 Reply)
Discussion started by: vivek d r
1 Replies

10. Shell Programming and Scripting

Error in eval eval command to print html tags

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
HTTP_BUILD_URL(3)							 1							 HTTP_BUILD_URL(3)

http_build_url - Build a URL

SYNOPSIS
string http_build_url ([mixed $url], [mixed $parts], [int $flags = HTTP_URL_REPLACE], [array &$new_url]) DESCRIPTION
Build a URL. The parts of the second URL will be merged into the first according to the flags argument. PARAMETERS
o $url - (part(s) of) a URL in form of a string or associative array like parse_url(3) returns o $parts - same as the first argument o $flags - a bitmask of binary or'ed HTTP_URL constants; HTTP_URL_REPLACE is the default o $new_url - if set, it will be filled with the parts of the composed url like parse_url(3) would return RETURN VALUES
Returns the new URL as string on success or FALSE on failure. EXAMPLES
Example #1 A http_build_url(3) example <?php echo http_build_url("http://user@www.example.com/pub/index.php?a=b#files", array( "scheme" => "ftp", "host" => "ftp.example.com", "path" => "files/current/", "query" => "a=c" ), HTTP_URL_STRIP_AUTH | HTTP_URL_JOIN_PATH | HTTP_URL_JOIN_QUERY | HTTP_URL_STRIP_FRAGMENT ); ?> The above example will output: ftp://ftp.example.com/pub/files/current/?a=c SEE ALSO
parse_url(3), http_build_str(3). PHP Documentation Group HTTP_BUILD_URL(3)
All times are GMT -4. The time now is 11:17 AM.
Unix & Linux Forums Content Copyright 1993-2022. All Rights Reserved.
Privacy Policy