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Top Forums Shell Programming and Scripting Strange result of eval, how does eval really work with ssh? Post 302519466 by summer_cherry on Wednesday 4th of May 2011 05:22:54 AM
Old 05-04-2011
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
Code:
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
Code:
#!/bin/bash
eval ssh remotehost date
eval ssh remotehost ls

below script works also well
Code:
echo "ls
ls -l" | while read line;do
eval $line
done

then below script has issue that only first line of command got executed
Code:
echo "ssh remotehost date
ssh remotehost ls" | while read line;do
eval $line
done

i was thinking maybe eval break the loop, but below script do print out the "-----" line

Code:
echo "ssh remotehost date
ssh remotehost ls" | while read line;do
eval $line
echo "----"
done

so what wrong here, please kindly help.

Last edited by summer_cherry; 05-04-2011 at 06:26 AM.. Reason: wrong title
 

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eval(1T)						       Tcl Built-In Commands							  eval(1T)

__________________________________________________________________________________________________________________________________________________

NAME
eval - Evaluate a Tcl script SYNOPSIS
eval arg ?arg ...? _________________________________________________________________ DESCRIPTION
Eval takes one or more arguments, which together comprise a Tcl script containing one or more commands. Eval concatenates all its argu- ments in the same fashion as the concat command, passes the concatenated string to the Tcl interpreter recursively, and returns the result of that evaluation (or any error generated by it). Note that the list command quotes sequences of words in such a way that they are not further expanded by the eval command. EXAMPLE
This procedure acts in a way that is analogous to the lappend command, except it inserts the argument values at the start of the list in the variable: proc lprepend {varName args} { upvar 1 $varName var # Ensure that the variable exists and contains a list lappend var # Now we insert all the arguments in one go set var [eval [list linsert $var 0] $args] } KEYWORDS
concatenate, evaluate, script SEE ALSO
catch(1T), concat(1T), error(1T), list(1T), subst(1T), tclvars(1T) ATTRIBUTES
See attributes(5) for descriptions of the following attributes: +--------------------+-----------------+ | ATTRIBUTE TYPE | ATTRIBUTE VALUE | +--------------------+-----------------+ |Availability | SUNWTcl | +--------------------+-----------------+ |Interface Stability | Uncommitted | +--------------------+-----------------+ NOTES
Source for Tcl is available on http://opensolaris.org. Tcl eval(1T)
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