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  • How to handle inputs in a C shell program during exec

    - by hits_lucky
    I am currently writing my own shell program. This simple shell can just execute commands. When executing commands like vi or calc which require input from the terminal , the command is getting executed and is waiting for the input from the user. But I am unable to give any input on the screen. How should the input be handled during the fork and exec. Here is the piece of code which is executing commands: if((pid = fork()) < 0) { perror("Fork failed"); exit(errno); } if(pid == 0) { // Child process if(execvp(arguments[0], arguments) == -1) { child_status = errno; switch(child_status) { case ENOENT: printf(" command not found \n"); break; } exit(errno); } } else { // parent process int wait_stat; if(waitpid(pid , &wait_stat, WNOHANG) == -1) { printf(" waitpid failed \n"); return; } } } ~ Thanks,

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  • How do I list all cron jobs for all users?

    - by yukondude
    Is there a command or an existing script that will let me view all of a *NIX system's scheduled cron jobs at once? I'd like it to include all of the user crontabs, as well as /etc/crontab, and whatever's in /etc/cron.d. It would also be nice to see the specific commands run by run-parts in /etc/crontab. Ideally, I'd like the output in a nice column form and ordered in some meaningful way. I could then merge these listings from multiple servers to view the overall "schedule of events." I was about to write such a script myself, but if someone's already gone to the trouble...

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  • join 3 files by first Column with awk ?

    - by noinflection
    i have three similar files, they are all like this: File A ID1 Value1a ID2 Value2a . . . IDN Value2n and i want an output like this Output ID1 Value1a Value1b Value1c ID2 Value2a Value2b Value2c ..... IDN ValueNa ValueNb ValueNc Looking to the first line, i want value1A to be the value of id1 in fileA, value1B the value of id1 in fileB, and so on which each field and each line. I thougth it like a sql join. I've tried several things but none of them where even close.

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  • What's wrong with this statement in perl?

    - by benjamin button
    print "$_", join(',',sort keys %$h),"\n"; It's giving me an error below: Use of uninitialized value in string at missing_months.pl line 36. 1,10,11,12 this print statement is present in a for loop as below: foreach my $num ( sort keys %hash ) { my $h = $hash{$num}; print "$_", join(',',sort keys %$h),"\n"; }

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  • appending text to all files that starts with a string

    - by learner135
    How do I append a string to all the files in a directory that starts with a particular string? I tried, cat mysig >> F* But instead of appending contents of mysig to all files starting with F, it creates a file named "F*". Obviously wildcard doesn't seem to work. Any alternatives? Thanks in advance. Edit: Also how do I delete this newly created file "F*" safely?. Using rm F* would delete all the files starting with F which I wouldn't want.

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  • Setting multiple jars in java classpath

    - by Chris Serra
    Is there a way to include all the jar files within a directory in the classpath? I'm trying java -classpath lib/*.jar:. my.package.Program and it is not able to find class files that are certainly in those jars. Do I need to add each jar file to the classpath separately?

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  • Why do I get strange output from Perl using SQL?

    - by benjamin button
    Here is my Perl code: foreach my $line (@tmp_field_validation) { chomp $line; my ($cycle_code,$cycle_month,$cycle_year)= split /\s*\|\s*/, $line; $cycle_code=~ s/^\s*(.*)\s*$/$1/; $cycle_month=~ s/^\s*(.*)\s*$/$1/; $cycle_year=~ s/^\s*(.*)\s*$/$1/; print "$line\n"; print "$cycle_code|$cycle_month|$cycle_year"; } Here is the output: 1 10 2009 1 10 2009|| What's wrong over here? I expected the pipes to be between the variables. Why are the pipes getting printed after all the three variables?

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  • Can I do everything in C that C++ and C# and Java can do?

    - by Sahat
    Is it possible to write in C programming language everything that you could write in other languages such as Java, C# or C++. If that's the case why don't schools these days teach C instead of Java? Ok the main reason why I am asking is because I don't want to tie down to a single programming language and platform (.NET and C# or Obj-C and Cocoa). Perhaps I am confusing a programming language with a framework? If anyone could clarify all this for me, I'd certainly vote for your answer.

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  • Shell script exiting the loop after calling another script

    - by Johnyy
    Hi Guys, I have a shell script s1 calling another script s2 in a loop. However s1 can not seem to continue the loop after s2 returns. Commenting out the line that calls s2 will enable the loop to continue. s2 does copy of one file, s1 checks conditions and copy several files using s2. Can anyone give a pointer what is going on here? ... while read line s2 param1 param2 param3 echo "copy done" done < $tempfile echo "out of loop" ... "copy done" is printed, so is "out of loop"

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  • SQL programming interface to external storage application

    - by Gopala
    My application is a non-relational database application with a tcl interface to retrieve data. I would like to add SQL programming interface to my application. Is there any library that converts SQL/PLSQL statements to API calls? It should also support stored procedures. SQLite(Embedded) has 'virtual table' mechanism that suits my requirement but it lacks stored procedure feature. -Gopala

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  • Security strategies for storing password on disk

    - by Mike
    I am building a suite of batch jobs that require regular access to a database, running on a Solaris 10 machine. Because of (unchangable) design constraints, we are required use a certain program to connect to it. Said interface requires us to pass a plain-text password over a command line to connect to the database. This is a terrible security practice, but we are stuck with it. I am trying to make sure things are properly secured on our end. Since the processing is automated (ie, we can't prompt for a password), and I can't store anything outside the disk, I need a strategy for storing our password securely. Here are some basic rules The system has multiple users. We can assume that our permissions are properly enforced (ie, if a file with a is chmod'd to 600, it won't be publically readable) I don't mind anyone with superuser access looking at our stored password Here is what i've got so far Store password in password.txt $chmod 600 password.txt Process reads from password.txt when it's needed Buffer overwritten with zeros when it's no longer needed Although I'm sure there is a better way.

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  • sendto is returning ENOBUF

    - by user338159
    Hi, I am currently running an old system on Tru64 which involves lots of UDP sockets using the sendto() function. The sockets are used in our code to send messages to/from various processes and then eventually on to a thick client app that is connected remotely. Occasionally the socket to the thick client gets stuck, this can cause some of these messages to get built up. My question is how can I determine the current buffer size, and how do I determine the maximum message buffer. The code below gives a snippet of how I set up the port and use the sendto function. /* need to adjust the maximum size we can send on this / / as it needs to be able to cope with the biggest / / messages we send / lenlen = sizeof(len) ; / allow double for when the system is under load */ len = 2 * C_MAX_MESSAGE_DATA_SIZE ; lpos_setsockopt(FATAL, msg_socket,SOL_SOCKET, SO_SNDBUF, &len, lenlen, &error_no) ; result = sendto( msg_socket, (char *)message, (int)message_len, flags, dest_addr, addrlen); Note. We have ported this application to Linux and the problem does not seem to appear there. Any help would be greatly appreciated. Regards

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  • Does knowing a Natural Language well help with Programming?

    - by Earlz
    We all hear that math at least helps a little bit with programming. My question though, does English or other natural language skills help with programming? I know it has to help with technical documentation, but what about actual programming? Are certain constructs in a programming language also there in natural languages? Does knowing how to write a 20 page research paper help with writing a 20k loc programming project?

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