Hi,
i want to check if a variable var1 is not a or b or c
pseudo code:
If NOT (var1 = a or var1 = b or var1 = c)
then
...
fi
I want to use POSIX complaint Korn shell, and for string comparison
For the following code, logical.sh
I gave execute permissions to the script, however it only seems to run good when run by 'sh ' and not by the script itself.
We run all our jobs without specifying 'sh ' ahead
$ chmod 777 logical.sh
$ logical.sh
Var : j
./logical.sh[3]: syntax error at line 6 : `}' unexpected
$ sh logical.sh
Var : j
var not in the list
Var : b
var in the list
$
Where am i going wrong?
Is it necessary to enclose the variable in double quotes but not the literals on the other side of comparison operator?
Hi:confused:,
I have a file that contains :
+-----------------------------------------------------------------------------+
LABEL: super1_fix
EFIX FILES: 1
ABSTRACT: epkg for touch command
PRE-REQUISITES: no
PACKAGER VERSION: 7
REBOOT REQUIRED: no
BUILD BOOT... (4 Replies)
I'm would to create a script that would give me the results below.
Please note the spaces in the log file are actually commas(",".)
Log file Data
0:00 21:15 899 43 31 12 25.39
0:00 21:20 736 34 19 15 35.39
0:00 21:20 776 41 28 13 ... (3 Replies)
Please tell me how to nest logical expressions in bash. I would like to nest logical expressions for arguments of the "test" command on bash.
The following pseudo-code shows my intention.
// pseudo code
if (exp1 AND (exp2 OR exp3))
{
Output true;
}
else
{
Output false;
}
... (11 Replies)
Hello all. This is my first post/question on this site.
I’m a new Systems Analyst with previous experience with BASH. Although now I'm using AIX, and I’m trying to get a feel for the Korn shell (for those of you that don’t know AIX only uses the KORN shell).
I hope I put this into the correct... (10 Replies)
I have code as follows to perform some validations on C++ and Javascript files:
if || || ; then
However, when I want to add other extensions as well, say "py" or "sql", then the repeated OR starts to look contrived. I know I can use the -o operator to abbreviate the code a little bit, but... (14 Replies)
The POSIX shell standard grammar rules are at
Shell Command Language
I am trying to understand Rule 7 and I don't. I think there may be some mistakes there. I am not complaining about the standard; rather, I am concerned that my perception is wrong, and I don't understand something important.... (3 Replies)
Hi all...
This is more of a concensus question than help...
As many of you know I am experimenting with the limitations of Pure POSIX shell scripting.
Q: Is the directory /bin considered part of the Pure POSIX shell or must I stick entirely with the builtins only?
The reason is I... (2 Replies)
Hi all,
I am learning POSIX shell programming, and the book I read, uses the let command for integer arithmetic.
I have downloaded and use the shellcheck program on Linux.
This programs says:
In POSIX sh, 'let' is undefined.
See the screenshot attached.
What is the POSIX... (1 Reply)
Hi all...
This is just a fun project to see if it is possible to get a square root of a positive integer from 1 to 9200000 to 6 decimal places on a 64 bit architecture machine.
It is coded around dash and the results show the values from 0 to 10000.
Complex numbers can easily be catered for by... (3 Replies)
Hi all...
Apologies for any typos, etc...
This took a while but it didn't beat me...
Although there are many methods of generating random numbers in a POSIX shell this uses integer maths and a simple C source to create an executable to get epoch to microseconds accuracy if it is needed. I take... (8 Replies)
Discussion started by: wisecracker
8 Replies
LEARN ABOUT PHP
empty
EMPTY(3) 1 EMPTY(3)empty - Determine whether a variable is emptySYNOPSIS
bool empty (mixed $var)
DESCRIPTION
Determine whether a variable is considered to be empty. A variable is considered empty if it does not exist or if its value equals FALSE.
empty(3) does not generate a warning if the variable does not exist.
PARAMETERS
o $var
- Variable to be checked
Note
Prior to PHP 5.5, empty(3) only supports variables; anything else will result in a parse error. In other words, the follow-
ing will not work: empty(trim($name)). Instead, use trim($name) == false.
No warning is generated if the variable does not exist. That means empty(3) is essentially the concise equivalent to !isset($var)
|| $var == false.
RETURN VALUES
Returns FALSE if $var exists and has a non-empty, non-zero value. Otherwise returns TRUE.
The following things are considered to be empty:
o "" (an empty string)
o 0 (0 as an integer)
o 0.0 (0 as a float)
o "0" (0 as a string)
o NULL
o FALSE
o array() (an empty array)
o $var; (a variable declared, but without a value)
CHANGELOG
+--------+---------------------------------------------------+
|Version | |
| | |
| | Description |
| | |
+--------+---------------------------------------------------+
| 5.5.0 | |
| | |
| | empty(3) now supports expressions, rather than |
| | only variables. |
| | |
| 5.4.0 | |
| | |
| | Checking non-numeric offsets of strings returns |
| | TRUE. |
| | |
+--------+---------------------------------------------------+
EXAMPLES
Example #1
A simple empty(3) / isset(3) comparison.
<?php
$var = 0;
// Evaluates to true because $var is empty
if (empty($var)) {
echo '$var is either 0, empty, or not set at all';
}
// Evaluates as true because $var is set
if (isset($var)) {
echo '$var is set even though it is empty';
}
?>
Example #2
empty(3) on String Offsets
PHP 5.4 changes how empty(3) behaves when passed string offsets.
<?php
$expected_array_got_string = 'somestring';
var_dump(empty($expected_array_got_string['some_key']));
var_dump(empty($expected_array_got_string[0]));
var_dump(empty($expected_array_got_string['0']));
var_dump(empty($expected_array_got_string[0.5]));
var_dump(empty($expected_array_got_string['0.5']));
var_dump(empty($expected_array_got_string['0 Mostel']));
?>
Output of the above example in PHP 5.3:
bool(false)
bool(false)
bool(false)
bool(false)
bool(false)
bool(false)
Output of the above example in PHP 5.4:
bool(true)
bool(false)
bool(false)
bool(false)
bool(true)
bool(true)
NOTES
Note
Because this is a language construct and not a function, it cannot be called using variable functions.
Note
When using empty(3) on inaccessible object properties, the __isset() overloading method will be called, if declared.
SEE ALSO isset(3), __isset(), unset(3), array_key_exists(3), count(3), strlen(3), The type comparison tables.
PHP Documentation Group EMPTY(3)