Hi,
I have a script called sam.sh which consists of a single echo statement like this
#/usr/bin/ksh
echo "Mani"
I changed the mode for the script by giving chmod a+x sam.sh.
If I want to execute the scrpt by just giving the name at the command line "sam.sh", what should I necessarily do?... (3 Replies)
If I did indeed grep something out of it, why woudln't $result show nothing?
When I do $? , it does show success...
What is the proper syntax so that $result shows actual thing it's grepping out?
result=`(ssh $host tail -1 /something/somethingelse) | egrep -i "value" >dev/null`
#echo... (3 Replies)
I would like to know:
1. How is `command` used?
2. How is '$command' used?
For example, a script file that checks for apache tomcat processes that I created has the following lines:
test
set suffix=` grep "6.0.18"`
set command = `ps -ef $suffix`
echo $command //?? hoping this... (2 Replies)
In bash scripts please can someone tell me if the below is the correct syntax for comparing integers and strings;
for integers -
if ;then
for strings -
if ; then
Thanks
Calypso (4 Replies)
Hi
How to call a shell scripting through a Perl scripting? Actually I need some value from Shell scripting and passes in the Perl scripting. So how can i do this? (2 Replies)
Hey I have to create a unix script that when run uses the 'man' command to print out the command information of commands passed as arguments. I have the basic pseudo code, but I don't know how to implement a loop. Any help is greatly appreciated. Cheers.
short-manual <ls cc pwd>... (3 Replies)
Hi,
I am very new to this forum, can any one tell me which is the very basic certification on unix shell scripting?
please give me an advice on this. (1 Reply)
Discussion started by: Manjesh
1 Replies
LEARN ABOUT REDHAT
system
SYSTEM(3) Linux Programmer's Manual SYSTEM(3)NAME
system - execute a shell command
SYNOPSIS
#include <stdlib.h>
int system(const char *string);
DESCRIPTION
system() executes a command specified in string by calling /bin/sh -c string, and returns after the command has been completed. During
execution of the command, SIGCHLD will be blocked, and SIGINT and SIGQUIT will be ignored.
RETURN VALUE
The value returned is -1 on error (e.g. fork failed), and the return status of the command otherwise. This latter return status is in the
format specified in wait(2). Thus, the exit code of the command will be WEXITSTATUS(status). In case /bin/sh could not be executed, the
exit status will be that of a command that does exit(127).
If the value of string is NULL, system() returns nonzero if the shell is available, and zero if not.
system() does not affect the wait status of any other children.
CONFORMING TO
ANSI C, POSIX.2, BSD 4.3
NOTES
As mentioned, system() ignores SIGINT and SIGQUIT. This may make programs that call it from a loop uninterruptable, unless they take care
themselves to check the exit status of the child. E.g.
while(something) {
int ret = system("foo");
if (WIFSIGNALED(ret) &&
(WTERMSIG(ret) == SIGINT || WTERMSIG(ret) == SIGQUIT))
break;
}
Do not use system() from a program with suid or sgid privileges, because strange values for some environment variables might be used to
subvert system integrity. Use the exec(3) family of functions instead, but not execlp(3) or execvp(3). system() will not, in fact, work
properly from programs with suid or sgid privileges on systems on which /bin/sh is bash version 2, since bash 2 drops privileges on
startup. (Debian uses a modified bash which does not do this when invoked as sh.)
The check for the availability of /bin/sh is not actually performed; it is always assumed to be available. ISO C specifies the check, but
POSIX.2 specifies that the return shall always be non-zero, since a system without the shell is not conforming, and it is this that is
implemented.
It is possible for the shell command to return 127, so that code is not a sure indication that the execve() call failed.
SEE ALSO sh(1), signal(2), wait(2), exec(3)
2001-09-23 SYSTEM(3)
09-18-2014
