Probably a simple one.
Basically I am retrieving a number from a file - setting a variable against it and then incrementing this by 1 and using this as an entry number in a log file for messages. I need the variable to re-evalute itself each time I call it so I get the latest number in the file -... (1 Reply)
I have variables:
FOO="Text"
BAR="FOO"
I'd like to be able to evaluate the variable named as the value of $BAR.
echo $FOO
Text
echo $BAR
FOO
This is what I'd like to do:
echo ${$BAR} (this won't work)
Text (3 Replies)
How to evaluate the value of a variable ?
For example:
a=var
$a=value !!!error happens!!!
I want to evaluate var=value, how to realize it?
Thanks!
---------- Post updated at 03:37 AM ---------- Previous update was at 02:22 AM ----------
I am using linux bash.
a=var
$a=value... (4 Replies)
Hi,
I am trying to do evaluate one numerical string after substitution.
++++++++++++++++==
What I have = "7.04+2.3Xlog(0.72e-6X1.0e6)X1.9596"
What I need = evaluate 7.04+2.3*log(0.72e-6*1.0e6)*1.9596 = 5.55941
what I am doing;
echo "7.04+2.3Xlog(0.72e-6X1.0e6)X1.9596" | awk... (2 Replies)
Hi,
I'm trying to use a config file to define frequencies for checking log files. If the config file contains a frequency it will be used else a default value. The format of the config file (and hence the environment variable) is
FREQ_log_logname=value
A test shell script as below:... (2 Replies)
I have the following simplified code that I am planning on putting into a larger shell script. I have been butchering it to try and make work amongst google searches and reading awk documentation.
amixer sset Master toggle | awk '{ if ( /^ Front Left/ { print $7 } == // ) print "MUTED" }'I... (2 Replies)
Simple enough problem I think, I just can't seem to get it right.
The below doesn't work as intended, it's just a function defined in a much larger script:
CheckValues() {
for field in \
Group_ID \
Group_Title \
Rule_ID \
Rule_Severity \
... (2 Replies)
I'm using korn shell and I am wondering if it's possible to use a parameter passed into a function to build a variable name in a configuration file. I have the function in one source file, I'd like to have a global configuration file instead of hardcoding logins to each script.
So I have a... (7 Replies)
Hi,
I am trying to set a variable that has time the format desired. And my intention is to echo variable (instead of actual date command) everytime I like to echo date. Please take a look at below code.
$NOW=''
echo $NOW
After 5 minutes
$echo $NOW
Issue here is , I am not... (2 Replies)
I am trying to write a simple function to select values from a database and assign them to variables. It can have any number of arguments sent into it, and I want to assign the value retrieved to a different variable name for each argument sent in. So my code looks something like this:
... (6 Replies)
Discussion started by: DJR
6 Replies
LEARN ABOUT PHP
eval
EVAL(3) 1 EVAL(3)eval - Evaluate a string as PHP codeSYNOPSIS
mixed eval (string $code)
DESCRIPTION
Evaluates the given $code as PHP.
Caution
The eval(3) language construct is very dangerous because it allows execution of arbitrary PHP code. Its use thus is discouraged.
If you have carefully verified that there is no other option than to use this construct, pay special attention not to pass any user
provided data into it without properly validating it beforehand.
PARAMETERS
o $code
- Valid PHP code to be evaluated. The code mustn't be wrapped in opening and closing PHP tags, i.e. 'echo "Hi!";' must be passed
instead of '<? echo "Hi!"; >'. It is still possible to leave and reenter PHP mode though using the appropriate PHP tags, e.g.
'echo "In PHP mode!"; ?>In HTML mode!<? echo "Back in PHP mode!";'. Apart from that the passed code must be valid PHP. This
includes that all statements must be properly terminated using a semicolon. 'echo "Hi!"' for example will cause a parse error,
whereas 'echo "Hi!";' will work. A return statement will immediately terminate the evaluation of the code. The code will be exe-
cuted in the scope of the code calling eval(3). Thus any variables defined or changed in the eval(3) call will remain visible
after it terminates.
RETURN VALUES eval(3) returns NULL unless return is called in the evaluated code, in which case the value passed to return is returned. If there is a
parse error in the evaluated code, eval(3) returns FALSE and execution of the following code continues normally. It is not possible to
catch a parse error in eval(3) using set_error_handler(3).
EXAMPLES
Example #1
eval(3) example - simple text merge
<?php
$string = 'cup';
$name = 'coffee';
$str = 'This is a $string with my $name in it.';
echo $str. "
";
eval("$str = "$str";");
echo $str. "
";
?>
The above example will output:
This is a $string with my $name in it.
This is a cup with my coffee in it.
NOTES
Note
Because this is a language construct and not a function, it cannot be called using variable functions.
Tip
As with anything that outputs its result directly to the browser, the output-control functions can be used to capture the output of
this function, and save it in a string (for example).
Note
In case of a fatal error in the evaluated code, the whole script exits.
SEE ALSO call_user_func(3).
PHP Documentation Group EVAL(3)