At first glance you might think that because the parameters to the echo are placed within double quotes that there'd be no expansion of the splat (*) in the expression command. However, the shell treats everything between backquotes as an independent string, and thus it's contents need to be further protected.
You should be able to code it this way if using a backslash bothers you:
Further info if you need it....
If the splat isn't escaped or quoted within the backtick string, the shell will expand the "wildcard" to be all files in the current working directory and the expression command will generate a syntax error.
Last edited by agama; 07-29-2011 at 11:33 PM..
Reason: further clarification at end
Hello!
I want to evaluate some mathematical expressions in a script and I try to use 'expr' command.
Unfortunatally, when I have, for example,
expr 8.2 + 6
the result is 'expr: non-numeric argument'
Why ?
I work on SunOs 5.7.
Thanks in advance
Nathe (5 Replies)
i am new to shell programming, currently using redhat linux of version
2.4.20-8.
i have problem in executing expr command in the following shell script
$ x=5
$ x='expr $x + 1'
$ echo $x
the output is displaying always
expr $x + 1
Pls guide me for the above query (3 Replies)
What is the difference between test expr VS .
For example :
if test 5 -eq 6
echo "Wrong"
and
if
echo "Wrong"
bot will give the same output as Wrong.
Now, what is the difference between these two? though they are producing the same result why we need two?
Any answer will be... (2 Replies)
I'm trying to check if a variable'd string is only one character and use that in an if statement the only way I could find is:
$expr "${var}" : . # expr STRING : regrep
where the "." is the grep wildcard for any single character.
Whats wrong with my code here and is there a... (3 Replies)
Hey there
i want to subtract the content from $b from $a. Each variable has got 18 values (normal numbers from 0 - 99).
How can i subtract them? I know i have to use the expr command, this is what i have till now:
a=`cat Tabelle.dat | awk {'print $4'} | awk -F: {'print $1'}`
b=`cat... (1 Reply)
Hi All,
I'm writing a shell script in KSH, where I want to store the filename, total record count and actual record count of all the source files. The source files reside in 4 different sub-folders under the same root folder.
Below is code:
#!/usr/bin/ksh... (6 Replies)
HI there
I am trying to understand Shell scripting to create my own, I am attempting a few examples can anyone tell me what this means?n=$( expr $n + 1)Tried looking on the internet, but just cannot find its anywhere :( .Help please (4 Replies)
Discussion started by: steve2015
4 Replies
LEARN ABOUT PHP
escapeshellcmd
ESCAPESHELLCMD(3) 1 ESCAPESHELLCMD(3)escapeshellcmd - Escape shell metacharactersSYNOPSIS
string escapeshellcmd (string $command)
DESCRIPTION escapeshellcmd(3) escapes any characters in a string that might be used to trick a shell command into executing arbitrary commands. This
function should be used to make sure that any data coming from user input is escaped before this data is passed to the exec(3) or system(3)
functions, or to the backtick operator.
Following characters are preceded by a backslash: #&;`|*?~<>^()[]{}$, x0A and xFF. ' and " are escaped only if they are not paired. In
Windows, all these characters plus % are replaced by a space instead.
PARAMETERS
o $command
- The command that will be escaped.
RETURN VALUES
The escaped string.
EXAMPLES
Example #1
escapeshellcmd(3) example
<?php
// We allow arbitrary number of arguments intentionally here.
$command = './configure '.$_POST['configure_options'];
$escaped_command = escapeshellcmd($command);
system($escaped_command);
?>
Warning
escapeshellcmd(3) should be used on the whole command string, and it still allows the attacker to pass arbitrary number of argu-
ments. For escaping a single argument escapeshellarg(3) should be used instead.
SEE ALSO escapeshellarg(3), exec(3), popen(3), system(3), backtick operator.
PHP Documentation Group ESCAPESHELLCMD(3)