10 More Discussions You Might Find Interesting
1. Shell Programming and Scripting
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
2. Shell Programming and Scripting
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
3. Shell Programming and Scripting
Hello All,
Since my variables are nested I use eval to populate the data.
I have an ambiguity here when eval is used along with &
say I have the below variable
url="www.unix.com" , this come from function call as argument.
I want to take this into another variable say... (6 Replies)
Discussion started by: sathyaonnuix
6 Replies
4. Shell Programming and Scripting
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
5. Shell Programming and Scripting
hi all,
Am trying to add some code to a ksh script and i dont understand how an eval function is used :
_var=$1
_conceal=$2
eval _val=\$${_var}
can someone shed some light on what the eval function in the above context means/does ??
thanks. (4 Replies)
Discussion started by: cesarNZ
4 Replies
6. Shell Programming and Scripting
I am trying to expand the variable $user in my alias command and tried
several variations of eval but can't seem to get it to work.
The end result should be either:
oracle_user='sudo su - oracle ' or oracle_user='sudo su - oracle1 '
user=$(grep '^oracle:' /etc/passwd | cut... (5 Replies)
Discussion started by: BeefStu
5 Replies
7. UNIX for Advanced & Expert Users
Hi,
I have snippet like the following
x="1"
prompt1="hi"
if I say
eval echo \$prompt$x then it is giving o/p "hi"
if I say `eval echo \$prompt$x` here it is giving 1 !
if I add one more escape character i.e.
`eval echo \\$prompt$x` then it is giving "hi"
Can you please... (3 Replies)
Discussion started by: shahnazurs
3 Replies
8. Shell Programming and Scripting
Hi, I have two files "foo" and "bar"
$ cat foo
a is \$a and b is \$b
$ cat bar
car tree
using the below 'while' loop I expect the output to be: a is car and b is tree
while read a b; do
eval echo $(cat foo) # o/p: a is $a and b is $b
eval "echo $(eval "cat foo")"... (1 Reply)
Discussion started by: royalibrahim
1 Replies
9. Shell Programming and Scripting
Hi All,
I'm running some encrypted data through a script I wrote. In order to do this, I'm using eval to resolve some of my variables. At the moment, when I use eval to resolve, it strips out some of my encrypted values, and totally drops some others. For example if I have the value ab1"3 it drops... (1 Reply)
Discussion started by: Khoomfire
1 Replies
10. Shell Programming and Scripting
Hi,
Is there any way that I can eval the following -
eval abc.csv=def.csv
I am getting the - bash: command not found error.
thanks. (3 Replies)
Discussion started by: ttshell
3 Replies
SQL::Eval(3) User Contributed Perl Documentation SQL::Eval(3)
NAME
SQL::Eval - Base for deriving evalution objects for SQL::Statement
SYNOPSIS
require SQL::Statement;
require SQL::Eval;
# Create an SQL statement; use a concrete subclass of
# SQL::Statement
my $stmt = MyStatement->new("SELECT * FROM foo, bar",
SQL::Parser->new('Ansi'));
# Get an eval object by calling open_tables; this
# will call MyStatement::open_table
my $eval = $stmt->open_tables($data);
# Set parameter 0 to 'Van Gogh'
$eval->param(0, 'Van Gogh');
# Get parameter 2
my $param = $eval->param(2);
# Get the SQL::Eval::Table object referring the 'foo' table
my $fooTable = $eval->table('foo');
DESCRIPTION
This module implements two classes that can be used for deriving concrete subclasses to evaluate SQL::Statement objects. The SQL::Eval
object can be thought as an abstract state engine for executing SQL queries, the SQL::Eval::Table object can be considered a *very* table
abstraction. It implements method for fetching or storing rows, retrieving column names and numbers and so on. See the "test.pl" script as
an example for implementing a concrete subclass.
While reading on, keep in mind that these are abstract classes, you *must* implement at least some of the methods describe below. Even
more, you need not derive from SQL::Eval or SQL::Eval::Table, you just need to implement the method interface.
All methods just throw a Perl exception in case of errors.
Method interface of SQL::Eval
new Constructor; use it like this:
$eval = SQL::Eval->new(\%attr);
Blesses the hash ref \%attr into the SQL::Eval class (or a subclass).
param Used for getting or setting input parameters, as in the SQL query
INSERT INTO foo VALUES (?, ?);
Example:
$eval->param(0, $val); # Set parameter 0
$eval->param(0); # Get parameter 0
params Likewise used for getting or setting the complete array of input parameters. Example:
$eval->params($params); # Set the array
$eval->params(); # Get the array
table Returns or sets a table object. Example:
$eval->table('foo', $fooTable); # Set the 'foo' table object
$eval->table('foo'); # Return the 'foo' table object
column Return the value of a column with a given name; example:
$col = $eval->column('foo', 'id'); # Return the 'id' column of
# the current row in the
# 'foo' table
This is equivalent and just a shorthand for
$col = $eval->table('foo')->column('id');
Method interface of SQL::Eval::Table
new Constructor; use it like this:
$eval = SQL::Eval::Table->new(\%attr);
Blesses the hash ref \%attr into the SQL::Eval::Table class (or a subclass).
row Used to get the current row as an array ref. Do not mismatch getting the current row with the fetch_row method! In fact this method
is valid only after a successfull "$table->fetchrow()". Example:
$row = $table->row();
column Get the column with a given name in the current row. Valid only after a successfull "$table->fetchrow()". Example:
$col = $table->column($colName);
column_num
Return the number of the given column name. Column numbers start with 0. Returns undef, if a column name is not defined, so that
you can well use this for verifying valid column names. Example:
$colNum = $table->column_num($colNum);
column_names
Returns an array ref of column names.
The above methods are implemented by SQL::Eval::Table. The following methods aren't, so that they *must* be implemented by concrete
subclassed. See the "test.pl" script for example.
fetch_row
Fetches the next row from the table. Returns "undef", if the last row was already fetched. The argument $data is for private use of
the concrete subclass. Example:
$row = $table->fetch_row($data);
Note, that you may use
$row = $table->row();
for retrieving the same row again, until the next call of "fetch_row".
push_row
Likewise for storing rows. Example:
$table->push_row($data, $row);
push_names
Used by the CREATE TABLE statement to set the column names of the new table. Receives an array ref of names. Example:
$table->push_names($data, $names);
seek Similar to the seek method of a filehandle; used for setting the number of the next row being written. Example:
$table->seek($data, $whence, $rowNum);
Actually the current implementation is using only "seek($data, 0,0)" (first row) and "seek($data, 2,0)" (last row, end of file).
truncate
Truncates a table after the current row. Example:
$table->truncate($data);
INTERNALS
The current implementation is quite simple: An SQL::Eval object is an hash ref with only two attributes. The "params" attribute is an array
ref of parameters. The "tables" attribute is an hash ref of table names (keys) and table objects (values).
SQL::Eval::Table instances are implemented as hash refs. Used attributes are "row" (the array ref of the current row), "col_nums" (an hash
ref of column names as keys and column numbers as values) and "col_names", an array ref of column names with the column numbers as indexes.
MULTITHREADING
All methods are working with instance-local data only, thus the module is reentrant and thread safe, if you either don't share handles
between threads or grant serialized use.
AUTHOR AND COPYRIGHT
This module is Copyright (C) 1998 by
Jochen Wiedmann
Am Eisteich 9
72555 Metzingen
Germany
Email: joe@ispsoft.de
Phone: +49 7123 14887
All rights reserved.
You may distribute this module under the terms of either the GNU General Public License or the Artistic License, as specified in the Perl
README file.
SEE ALSO
SQL::Statement(3)
perl v5.12.1 2010-05-06 SQL::Eval(3)