Programming :: Perl About System Command / Fails If The Standard Shell Is Dash And Not Bash?
Jun 30, 2011
I am trying to fix a perl script, and I really suck at perl. But I think this problem will be easy for people who know it.
The problem is, I have an old setup script someone wrote many years ago. It fails if the standard shell is dash and not bash. The only way I've gotten it to work is to point /bin/sh to bash. I looked thru the script and it uses "system" many places, and I think that's the problem.
I searched for it and found this link:url
My plan is to include this function:
Code:
sub system_bash {
my @args = ( "bash", "-c", shift );
system(@args);
}
Then I could simply change all calls to system into system_bash and it should work?
The parameter to the system calls is usually some variable. What if the parameter is a list already? Do I need to test for it somehow, and if it's a list, prepend "bash" and "-c" to the list? How do I do that?
In the script there are lots of places like this:
my $error = system($cmd);
if ($error) {
die/warn "some error message";
}
Shouldn't there be a return in the system_bash function?
when I execute the command from the shell command line - it works and no error code.if I do the exact same command from a perl file - it fails with code 32512.the file is created from the same perl script that runs the command that fails. file permission is 0664.
This pretend to be a script for rename a lot of files automatically. So I put the list of files in an array named @lista. But, as you can see, at the end of the command I use a sed filter to print out a backslash for those files that have spaces in their names, so the path for those files could be rightly interpreted.
But there's no way I could print a backslash. It works well when I use the Perl's sed substitution s///, but I need every path in the array to be fixed.
I'd like to add that the bash command works perfectly well alone. I mean outside the Perl script.
I wanted to find and replace a string from a perl file. I have written a script in bash which runs the following command.
perl -pi -e "s/$findstring/$replacestring/" testfile where as $findstring = print F_WC_TMP"$line "; and $replaceString = $line = join ' ', split ' ', $line; print F_WC_TMP"$line ";
But when I am running the above command, i think it is replacing the $findstring with the above mentioned string and hence it contains a $line, it is looking for the variable $line and not finding the exact string. I am confused about how to search for a string that contains $ in it and replace it with another $string.
I am running a Java application on the command line bash terminal under Mint Debian. I have JDK1.6.0_22 installed 64-bit, and the OS is 64-bit too. I have a few JAR files in the directory and a few native LWJGL libraries. When I run the application using the command line, all works fine. Lets assume my directory where the files are is called /home/riz/MyGame. I change to that directory and this is the command I use code...
I'm trying to call a system command in perl and am having an issue with it.
Here's an example of a command i'd like to call: Code: sed -i '4 c192.168.1.4 www.something.com' hosts this is the section in my perl script where I create the variable and call it: Code: $doit = `sed -i '$line c$ip $host hosts'`system($doit); The $line, $ip, and $host variables are working fine becasue I can replace that section with "prints" and they come out fine. I imagine the problem is where I am creating the $doit variable.
I wonder if there is anyway to make a user-defined bash shell function global, meaning the function can be use in any bash shell scripts, interactively or not. This is what I attempted:
Trying to create a small script that will read user's input, test if user entered some input and if not display some message or display a text using user's input.
The script is the following but i get an error saying "[: 6: =: argument expected"
I am having all sorts of trouble trying to assign a variable within an awk script with the system command. I know there is a lot of ways around this problem, but for efficiency reasons, I would like to, within my awk script, do something like
system(x=3)
or
system(x=NR)
and, latter on the shell script which calls the awk script, use the variable $x. But nothing is passed to x. I have already tried things like
command = "x=3" system(command)
and also used a pipeline within the system to pipe it to /bin/sh In fact tried a lot of stuff like that, using $(( )) etc etc etc I can create directories e write to files (yes, i could write to a file and read from there, but I dont think it is efficient, plus I am puzzled).
What options should I use when I'm using the sort command to sort the top 5 CPU processes (ps -eo user,pid,ppid,%cpu,%mem,fname | sort ??? | head -5) showing max to min usage?
Is there a way to use exec, but if exec fails to go on with the script?
Example:
Code: #!/usr/bin/env bash exec startx echo "Starting of X failed"
If startx fails, the echo will be seen on the screen. I tried all kind of stuff, but guess it ain't of much use to post it here. I searched the web, but searching for "exec and bash" in one sentence does give results which are not what i am looking for.
I'm trying to write a bash script program in the Linux command terminal that will write to a fellow user and then continue reading down the program. this is what i have (kind of explains the idea too):
#!/bin/sh
clear echo "this is before the write command" write jcummins this message should go to jerry echo "the message didn't send and this string will not appear" echo "it appears it has stopped at the write command"
i was attempting to "speed up boot time" by using the "dash" shell instead of "bash"there is a post on here which describes this.i installed the scripts and uhhhh....rebootednow it seems that i kinda sorta forgot to install "dash" before reboot and now ihave no system shell.no root user accessonly my regular user works, kinda...it seems that i cannot edit anything eitherit won't do any temp dataso with mc i cannot save any edited files.....prompt looks like thismichael@(none):i am hoping i just need to install dash....but with limited power at the command prompt this may be interesting.
Is there some type of functional way to read things in the Python shell interpreter similar to less or more in the bash (and other) command line shells?
Example:
Code:
>>> import subprocess >>> help(subprocess) ... [pages of stuff to read] ...
I'm hoping so as I hate scrolling and love how less works with simple keystrokes for page-up/page-down/searching etc.
i used ldap for authentication.now i have a perl script that users use it for login(contact.pl),then this script calls a shell script(ip.sh) for create iptables chain.
when i call that into contact.pl ,it just prints: usr/sbin/iptables but ip chains didn't change.what is problem? whenever run ip.sh in bash it works correctly
I want to compare the following two tab-delimited .txt files (both were subsets of the original files) by comparing Columns 3 and 4 simultaneously. It is easy to compare C3 because both C3s are just numbers. But how to compare C4s?Basically, in File1, "G,G" = G in File2, "C,C" = C in File2, "A,A" = A in File2, "T,T"= T in File2.In File2, A/T in Column4 just equals "A,T" or "T,A" in Column4 of File1. C/T in Column4 just equals "C,T" or "T,C" in Column4 of File1, and etc.
I wrote this script for bash & perl. If you run it in bash it should work. It changes title - (uuid) kernel - initrd ... to title - uuid UUID=the_uuid... kernel - initrd .... When I wrote it I replaced end of lines by . It's the second $block definition. But now I need to repair it, because I will work with the 1st $block definition. That is not to exclude end of lines, but leave it be untouched. Now when you escape the second $block definition, the code does not work. What I have to do to repair it working with multiline input data?
I'm trying to pull out sections from a bunch of files. For one file, I use:
Code: sed '/string1/,/string2/ !d' <filename.ext >newfilename.ext to pull out everything between two strings in the original file and put them in a new file.
I've been trying to figure out a way to more easily color text in Perl like I do on Bash on a Linux box. In bash, what I'll do is set color variables up to equal the escape sequence, then echo out with escape seqeunces to print it exactly how I want it. Typically I'll want a character or a word in a different color, not the whole line. For example
echo -n -e "My face is turning ${RED}red${UNCOLOR} like a lobster." In Perl with the term::ANSIColor module, it seems to just do a line. Am I being dense? Is there a way that I can do it like I do it in BASH that's fairly easy to read after the fact?
I've recently inherited a bunch of files at a new job and am trying to figure out some of the problems that have constantly popped up. The one i'm getting a huge headache with results from a bash script that is supposed to change a date format from a client populated txt field to one we want defined a certain way. Everything in the script works fine, except that one function. Below is the line i'm trying to manipulate, with date examples.
The one caveat is that the first date is non-static and changes daily. It is, however, always the current date. If it helps, the second date will always be a year away from the first date.My idea was to pull the current date via perl's DATE function, but...how to do it, and calculate a year away without throwing the rest of the bash script off? Any help would be appreciated. I'm sure it's a simple solution but i know absolutely nothing about these scripts and how they were written.
when I try to enter an escape sequence in the interactive mode of dash, it keeps on spewing out the <ESC> character as ^[ displayed in plain text instead of catching it as a control character. I vaguely remember encountering this on some UNIX shell but for the life of me I can't find anything on it. So how do I properly enter escape sequences in dash's interactive mode? (it supposedly supports vi line edit mode but I can't access it at all because of the ESC situation)It's not a make-or-break thing.
"When first starting, the shell inspects argument 0, and if it begins with a dash '-', the shell is also considered a login shell" - from the dash man page. Could someone please explain this to me in a way that I actually understand?
