Hello,
I have a script that does an scp to a server and then gets the number of process running on that server, the o/P should be stored in a variable for further processing
eval `echo "ssh -q $Infa_user@$host 'csh -c $CMD '"`
where
CMD="ps -ef | grep -i ${INFA_REPO} | grep -v grep | wc... (2 Replies)
Help !!
First, Thanks in Advance
Here is what I have
I have an environment Variable, let's call it v_VALUE.
v_VALUE="\$ORACLE_HOME/bin" Hence, the location is ORACLE_HOME is not evaluated. ORACLE_HOME happens to be /app/oracle/product/10.1.2
I need a method of returning the... (1 Reply)
Hi,
i have an issue with eval and variable assignment.
1) i have a date value in a variable and that date is part of a filename,
var1=20100331
file1=${var1}-D1-0092.xml.zip
file2=${var2}-D2-0092.xml.zip
file3=${var3}-D3-0092.xml.zip
i am passing the above variables to a script via... (11 Replies)
Hi Gurus,
I am having 2 parameters as below
parm1=value1
parm2=parm1
I want to evaluate parm1 value using eval echo \$$parm2 and later i want to assign this value to other variable which i will be using in if statement like :
if ]; then
do this.......
fi
could you please suggest... (5 Replies)
background : Solaris, ksh
metresult="ooo
> pp"
ts=89
eval append_${ts}="$metresult"
bash: pp: command not found
I want to create a variable which has in a part of its name a dynamically-established number (stored in another variable) usually I do this with eval command. The problem I... (5 Replies)
pattern1=book
{
x=1
eval echo \$pattern$x
}
book (this is the output)
But when I assign a variable to the output of the eval it doesn't work unless I prefix 2 times backslash before $ as shown below.
{
a=`eval echo \\$pattern$x`
echo $a
}
book
Why here twice "\" has to be... (3 Replies)
Is there a safe way to evaluate variable declarations within a script whether they come from a .conf file, user input, or stdin?
Example .conf file:
server=ftp.xxxx.com
port=21
user="$USER" # Hopefully allow this type of substitution
domain="$DOMAIN"
server="$(malicious... (4 Replies)
I want to do 2 things in single line that is evaluating a command to get return code and store $2 of awk if the command exit code is 0.
eval "ade desc ${filename}@@/<branch_name> | grep Version | awk '{print $2}' 2>&1 1>/dev/null"
ret=$?
echo "$ret $val"
if
then
... (3 Replies)
Perl::Critic::Policy::ErrorHandling::RequireCheckingRetuUserlContributed PPerl::Critic::Policy::ErrorHandling::RequireCheckingReturnValueOfEval(3)NAME
Perl::Critic::Policy::ErrorHandling::RequireCheckingReturnValueOfEval - You can't depend upon the value of "$@"/"$EVAL_ERROR" to tell
whether an "eval" failed.
AFFILIATION
This Policy is part of the core Perl::Critic distribution.
DESCRIPTION
A common idiom in perl for dealing with possible errors is to use "eval" followed by a check of $@/$EVAL_ERROR:
eval {
...
};
if ($EVAL_ERROR) {
...
}
There's a problem with this: the value of $EVAL_ERROR can change between the end of the "eval" and the "if" statement. The issue is object
destructors:
package Foo;
...
sub DESTROY {
...
eval { ... };
...
}
package main;
eval {
my $foo = Foo->new();
...
};
if ($EVAL_ERROR) {
...
}
Assuming there are no other references to $foo created, when the "eval" block in "main" is exited, "Foo::DESTROY()" will be invoked,
regardless of whether the "eval" finished normally or not. If the "eval" in "main" fails, but the "eval" in "Foo::DESTROY()" succeeds,
then $EVAL_ERROR will be empty by the time that the "if" is executed. Additional issues arise if you depend upon the exact contents of
$EVAL_ERROR and both "eval"s fail, because the messages from both will be concatenated.
Even if there isn't an "eval" directly in the "DESTROY()" method code, it may invoke code that does use "eval" or otherwise affects
$EVAL_ERROR.
The solution is to ensure that, upon normal exit, an "eval" returns a true value and to test that value:
# Constructors are no problem.
my $object = eval { Class->new() };
# To cover the possiblity that an operation may correctly return a
# false value, end the block with "1":
if ( eval { something(); 1 } ) {
...
}
eval {
...
1;
}
or do {
# Error handling here
};
Unfortunately, you can't use the "defined" function to test the result; "eval" returns an empty string on failure.
Various modules have been written to take some of the pain out of properly localizing and checking $@/$EVAL_ERROR. For example:
use Try::Tiny;
try {
...
} catch {
# Error handling here;
# The exception is in $_/$ARG, not $@/$EVAL_ERROR.
}; # Note semicolon.
"But we don't use DESTROY() anywhere in our code!" you say. That may be the case, but do any of the third-party modules you use have them?
What about any you may use in the future or updated versions of the ones you already use?
CONFIGURATION
This Policy is not configurable except for the standard options.
SEE ALSO
See thread on perl5-porters starting here: <http://www.xray.mpe.mpg.de/mailing-lists/perl5-porters/2008-06/msg00537.html>.
For a nice, easy, non-magical way of properly handling exceptions, see Try::Tiny.
AUTHOR
Elliot Shank "<perl@galumph.com>"
COPYRIGHT
Copyright (c) 2008-2011 Elliot Shank.
This program is free software; you can redistribute it and/or modify it under the same terms as Perl itself. The full text of this license
can be found in the LICENSE file included with this module.
perl v5.16.32014-0Perl::Critic::Policy::ErrorHandling::RequireCheckingReturnValueOfEval(3)