A few comments:
- why the multiple read?
- what are the + - signs in front of the regexes for?
- good, consequent indentation helps people (and YOU!) understand your code faster and easier
As an idea for you a small code snippet that does the same as your code presented (may be enhanced by e.g. error checking and debugging code):
hi!
i need to do a ksh script that uses a wile loop that is fed form below
while read line
do
some things
done < myfile
inside the while loop i need to read user input to ask the user what he wants to do, but "read" reads the file, and not the standard input
while read line
do
... (2 Replies)
Hello, i know how to retrieve a user input (read), and how to manage the different options (case statement).
But... could anybody show me a script that, if the user option is incorrect, don't allow to continue the excution, i.e., if the value entered is not 1 or 2, the script shows a question.
... (2 Replies)
Hello everybody!!!
I am writing my own rm command in unix.
I prompt the user to type if he wants to delete a file and then read what he typed.
But how do i check what he typed?
This is my program so far:
echo 'Delete prog1.c (y/n)?'
read yesOrNo
if yesOrNo == 'y'
then
rm prog1.c... (6 Replies)
I'm new to BASH and i'm trying to create a script which is simply put a large find and replace file. This is what I have so far
N=0
while read LINE ; do
N=$((N+1))
sed 's/'$2'/'$3'/g' $LINE > .temp
echo "Changes to file $N = $LINE"
echo 'The following changes... (5 Replies)
until
do
read -p "Invalid cars. Try againa" cars1
done
Ok i have the above code, im getting users input and if it doesnt match in the file the user has to try again untill its correct
But when i run this it gives me an error saying
./Cars.bash: line 43: (2 Replies)
Good Evening. I'm new to C. Can you please help me.
I'm creating an error checking function, user will input a string, this will check if the input is all alphabet or all letters only. If there is a digit or other special char, it will print Error then ask input from user again.
Here's my... (1 Reply)
Hi,
I need my script to check if the user enters 3 values if not 5 values to my script and alert if the input has any other number of values.
for example:
./myscript.sh 22 56 3221 - > correct
./myscript.sh 22 56 3221 45 777 -> correct
./myscript.sh 22 56 3221 45 -> incorrect
Please... (6 Replies)
I have a shell script, and its pretty much done, I decided to add a loop that ends or continues depending on user input. like "would you like to continue?" and if I hit y or yes it will run the loop again until I hit n or no and breaks out of the loop.
To be hones I didn't think I needed to add... (2 Replies)
Hi,
On my Java webpage which invokes the shell script has two checkboxes viz ...
apache
and
weblogic
apache require one parameter i.e apache home from the user while Weblogic requires three or five params from the user vi.z weblogic_home or <jdk_home, config_home & pid>, username and... (4 Replies)
How to check the user input to be valid using shell script?
The valid input is in the format like as follows.
1. It can only have r,w,x or a hyphen and nothing else.
2. ensure the r, w, x are in the correct order.
for example: rwxr-xr-x is a valid format.
Thanks (5 Replies)
Discussion started by: hyeewang
5 Replies
LEARN ABOUT SUSE
system
SYSTEM(3) Linux Programmer's Manual SYSTEM(3)NAME
system - execute a shell command
SYNOPSIS
#include <stdlib.h>
int system(const char *command);
DESCRIPTION
system() executes a command specified in command by calling /bin/sh -c command, 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(2) 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 command 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
C89, C99, POSIX.1-2001.
NOTES
If the _XOPEN_SOURCE feature test macro is defined, then the macros described in wait(2) (WEXITSTATUS(), etc.) are made available when
including <stdlib.h>.
As mentioned, system() ignores SIGINT and SIGQUIT. This may make programs that call it from a loop uninterruptible, 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 set-user-ID or set-group-ID 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 set-user-ID or set-group-ID 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.)
In versions of glibc before 2.1.3, the check for the availability of /bin/sh was not actually performed if command was NULL; instead it was
always assumed to be available, and system() always returned 1 in this case. Since glibc 2.1.3, this check is performed because, even
though POSIX.1-2001 requires a conforming implementation to provide a shell, that shell may not be available or executable if the calling
program has previously called chroot(2) (which is not specified by POSIX.1-2001).
It is possible for the shell command to return 127, so that code is not a sure indication that the execve(2) call failed.
SEE ALSO sh(1), signal(2), wait(2), exec(3)COLOPHON
This page is part of release 3.25 of the Linux man-pages project. A description of the project, and information about reporting bugs, can
be found at http://www.kernel.org/doc/man-pages/.
2004-12-20 SYSTEM(3)