Using bash, I'm trying to read a .properties file (name=value pairs), assigning an indirect variable reference for each line in the file.
The trick is that a property's value string may contain the name of a property that occurred earlier in the file, and I want the name of the 1st property to... (5 Replies)
The construct ${#parameter} returns the number of characters in the parameter and ${!parameter} specifies an indirect variable. My question is: How do I combine these two. What I want is ${#!parameter} but this gives an error.
Of course I can use:
dummy=${!parameter}
${#dummy}
but that's a... (0 Replies)
Ummm can anybody help me with this one?
Its prob quite simple.
I bascially have a file name say J1x2x3x7.dat
Im using the file name as a variable in a bash script. Want I want to do is extract most of the file name and make it a new variable expect with say one of the number now a... (2 Replies)
Hi,
I've got a small problem.
If varible A stores "B" and Variable B stores C,
How to get the value of variable B by using only Variable A..?
I tried the following but didnt work pease help..
$ var1=vikram
$ echo $var1
vikram
$ vikram=sampath
$ echo $vikram
sampath
$ echo... (6 Replies)
Hi
I have variable A_B=alpha
also var1="A"
var2="B"
I want to retrieve the value alpha using var1 and var2 , somthing like
echo ${${var1}_${var2}} that works. Obviously this is receiving syntax
error (6 Replies)
Hello,
is there a kind soul who can answer me, does the SH support double substitution known as indirect expansion similar to BASH? The syntax for bash is ${!var}.
For instance in bash I can write something like this:
VAR="value"
REF_VAR="VAR"
echo ${!REF_VAR}
and get the "value"... (1 Reply)
I have a file with two columns of numbers (member IDs):
1 1
2 1
3 1
4 2
5 4
6 1
7 5
8 3
9 2
Think of column 1 as the referee and column 2 as the referrer.
Is there a good way to backtrack who referred who? I would like an output, for this example here to be:
1 1
2 1
3 1
4 2 1 (2 Replies)
Sometimes it is handy to protect long scripts in C++.
The following syntax works fine for simple commands:
#define SHELLSCRIPT1 "\
#/bin/bash \n\
echo \"hello\" \n\
"
int main ()
{
cout <<system(SHELLSCRIPT1);
return 0;
}
Unfortunately for there are problems for:
1d arrays:... (10 Replies)
Trying to do so
echo "111:222:333" |awk -F: '{system("export TESTO=" $2)}'But it doesn't work (2 Replies)
Discussion started by: urello
2 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)