My system is Ubuntu 11.04 and shell is bash, I believe.
If you have BASH, you have for-loop:
This would be better than for file in * since it's less likely to match other things by accident and isn't going to ever cram too many arguments for for to handle into anything.
Hi,
I want to process all input files available into folder (C:\ShellPrg\InputFile\) Input files are abc.CSV , XYZ.zip (zip of CSV file), PQR.gz (zip of CSV file).
I want to check the extension of file, If its .zip/.gz then need to unzip the file as .CSV
I want to parse line by line of... (2 Replies)
Hi,
I would like to write a for loop that does the following:
I have a file called X.txt and other files called 1.txt,2.txt, .....,1000.txt.
I want to substitute the 6th column of the file X.txt with 1.txt and store the output as X.1. Then I want to do the same with X.txt and 2.txt and store... (0 Replies)
I would like to write a for loop that does the following:
I have a file called X.txt and other files called 1.txt,2.txt, .....,1000.txt.
I want to substitute the 6th column of the file X.txt with 1.txt and store the output as X.1. Then I want to do the same with X.txt and 2.txt and store the... (1 Reply)
I have a script where the the 9th line looks like this:
$filename=sprintf("250.1chr%d.ped", $N);
I want to modify this script 1000 times, changing 250.1chr%d.ped to 250.2chr%d.ped, 250.3chr%.ped.......and so on all the way to 250.1000chr%d.ped and store each output in files called
... (4 Replies)
I have 100 data files labelled 250.1.txt through 250.100.txt. The second column of the data files partially match (there is about %90 overlap). Each data file has 4 columns.
I want the merge all these text files by the matching values in the second column. In the output, the first column should... (1 Reply)
Hello,
So I have approximately 300 files of raw data (.txt) files that I am using to perform statistical analysis. I have been able to construct a Fortran program that is able to perform my statistical analysis on a file by file basis.
However, I now want to be able to loop program through... (19 Replies)
Hi,
I have 1000 text files in a folder that are labeled data1.txt all the way to data1000.txt. I want to write a small script that manipulates the text files in this way:
(1) cut the 2nd and 9th columns of the text files
(2) sort by the numerical value in the 9th column
(3) then save the rows... (3 Replies)
Hi all ,
i want to pass multiple files as input to a for loop
for i in file1 file2 file3
do
some awk action < $i >> $i.out
done
but im getting error in that for loop is the way i use to pass files to awk using for correct and
2.we can directly pass multiple files to awk as... (7 Replies)
Hi, I have written a script that allows me to repetitively play a music file $N times, which is specified through user input. However, if I want to exit the script before it has finished looping $N times, if I use CTRL+c, I have to CTRL+c however many times are left in order to complete the loop.... (9 Replies)
Hello!
Need help to write a Linux script that can be run from windows using command/Cygwin/any other way. I am new to scripting, actually i am trying to automate server health check like free disk space, memory along with few services status, if any services is not running then start services ,... (7 Replies)
Discussion started by: Sayed Ibrahim
7 Replies
LEARN ABOUT LINUX
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 (before including any header files), then the macros described in wait(2) (WEXITSTA-
TUS(), 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 3.27 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/.
2010-09-10 SYSTEM(3)