for cycle question Post: 302293391

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1. Shell Programming and Scripting

shell cycle

Hello I got a cycle in the script which open another scripts. if then action fi Scripts action will be running 2 times at the same time. Inside of action() is insert into the table. But what I want is that only first script can do insert into table. So how to do...

2. Shell Programming and Scripting

For cycle

Hello, I have files in a dir. I what to create a FOR cycle that will do this FOR <condition> do file=`ls <directory> | tail -1` echo $file mv -f $file <another dir> done What I want to now is what should I put in the <condition>. The condition I want is that the FOR will execute...

3. Shell Programming and Scripting

wildcard in a if cycle

hello everybody, I need help on putting a wildcard match inside an if condition (I'm using korn shell): if ] then echo ' ' echo ''$MYSEL' is not a correct option' echo ' ' else ..... i tried also #if -ne "``" and a lot of combinations of `"' but I didn't find the...

4. Shell Programming and Scripting

for cycle

Hello, I have a question: is there a way to have a "for" cycle done a certain number of times. For example in c++ I can do this: for (i=o;i<10;i++) and the cycle will be repeated 10 times. in UNIX for example I do this: for i in `cat /etc/host` do done and the cycle will be repeated...

5. Shell Programming and Scripting

Cycle for with for-then-else

Hi, i would like to insert a if-then-else function in to cycle for -------------- cat test -------------- # cat test ALFA BETA GAMMA ----------------------- This is my script: #!/bin/bash for i in $(cat test); if ; then echo "ok" else

6. Shell Programming and Scripting

For cycle and formatting stdout

Dear all, I want to create a table using a shell script. Hope someone can help. I created a variable that contains the path for different files. For all the files I want to do calculations and print it to stdout (or file) as a table. I tried this code: paths=`cat $tabdelim_file | awk...

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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)