Programming :: Write A Script Which Will Get A Number From STDIN?
Dec 15, 2008
I need to write a script which will get a number from STDIN and then with that number echo a set number of questions (its for a firewall config). Heres what I want the user to receive.
How many ports do you want open? 3
1. specify port: 80
2. specify port: 21
3. specify port: 23
In the background this will echo a command out to a text file which will read as follows:
open port 80
open port 21
open port 23
I've done this before but I've completely forgotten how
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Sep 9, 2010
Some help with this problem:Code:Write a function that counts the number of occurrences of a pair of letters in a string
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Jun 22, 2010
Often in bash we read lines from stdin in a loop and implicitly discard the remaining stdin by terminating the loop. Is it possible to discard it without terminating the loop? It could lead to smaller code.
Here's an example which uses two loops and below is the same algorithm assuming unwanted stdin can be discarded
Code:
found=
while read destination gateway _
do
[[ $destination = default ]] && found=yes && break
done <<< "$( route )"
[Code].....
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Mar 14, 2010
I have a small program that reads stdin from a pipe using fgets. Now fgets blocks for the first line but after that it will not block.
The code, my_echo.c -
int main(int argc, char **argv) { char buf [2000] ;
char* pc ; printf("hello ") ; while (1)
{ buf[0] = (char) 0 ;
pc = fgets(buf, sizeof(buf), stdin);
if (pc != NULL) printf("%s ",buf); } return 0; }
How its called
* In terminal window 1: ./my_echo < my_fifo
* In terminal window 2: echo "1234" > my_fifo
* In terminal window 1: prints hello then 1234.
* Checking with ksysguard or top shows that my_echo is consuming 40% of CPU time.
Adding a few printf's shows that the gets is not blocking and returns a null pointer.
* In terminal window 2: echo "qwerty" > my_fifo
* In terminal window 1 qwerty prints.
I want a read function that does in fact block so my program does not tie up CPU time, read does not block.
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Oct 10, 2010
[code]...
I've given the output from `df` on AWK's stdin. But what I wonder is if there's a way to get AWK to run `df` itself, produce the same output, and exit? Doesn't seem to be that simple. Here's some examples: Works for some reason, and I think only in Bash (nothing is required in the $()
[code]...
does AWK absolutely need *something* on stdin, before it begins to process the data? Can it be made to open a file or stream internally, act upon that as though it were the stdin, and exit?
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Aug 18, 2010
I'm trying to write a shell script that do ftp and download file periodically, this script should be called by a daemon running in the background.
the shell script "script.sh" is as follows:
Code:
yafc ftp://test:test@192.168.1.225:21 < commands
and the "commands" files is
Code:
d Root/md5* /
quit
if I run script.sh it will work just fine. But when the daemon software calls the "script.sh", the script will send ftp login request to the ftp server, but will not even answer the username or anything.
I believe it is something about child process redirection, but I don't know how to deal with it.
This problem is not only with yafc, it is the same with any ftp client or any application like telnet and so.
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Apr 28, 2010
I am trying to read one line at a time in perl and not wait for stdin eof to start the action:
Code:
foreach(<STDIN>){
<do something>
}
if i pipe ls into it, it waits for ls to be done before doing the action.
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Oct 20, 2010
I want to put a keystroke into another virtual terminal's stdin.A simple 'echo p > /dev/tty7' causes a p to appear on the console of tty7 but not the app running in tty7 to respond as though a p key had been pressed. Per the instructions of a fellow in the software forum I tried using an ioctl, but that returned a permissions error, even when I made the target VT's permissions 777 (and it had the same owner).
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Nov 24, 2010
I'm trying to write a program that will fork a series of FTP sessions. For each session, there should be separate input and output files associated with stdin and stdout/stderr.
I keep reading how I should be able to do that with dup2() in the child process before the execl(), but it's not working for me. Could someone please explain what I've done wrong? The program also has a 30-second sniper alarm for testing and killing of FTPs that go dormant for too long.
The code: (ftpmon.c)
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
[code]....
The output:
$ ftpmon
Connected to gila-crstest.gilacorp.com (172.16.20.8).
220 (vsFTPd 2.0.1)
ftp> waitpid(): Interrupted system call
Why am I getting the ftp> prompt? If the dup2() works, shouldn't it be taking input from my script and not my terminal? In stead, it does nothing, and winds up getting killed after 30 seconds. The log file is created, but it's empty after the run.
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Aug 8, 2010
I'm working on an application used for backup/archiving. That can be archiving contents on block devices, tapes, as well as regular files. The application stores data in hard packed low redundancy heaps with multiple indexes pointing out uniquely stored, (shared), fractions in the heap.
And the application supports taking and reverting to snapshot of total storage on several computers running different OS, as well as simply taking on archiving of single files. It uses hamming code diversity to defeat the disk rot, instead of using raid arrays which has proven to become pretty much useless when the arrays climb over some terabytes in size. It is intended to be a distributed CMS (content management system) for a diversity of platforms, with focus on secure storage/archiving. i have a unix shell tool that acts like gzip, cat, dd etc in being able to pipe data between applications.
Example:
dd if=/dev/sda bs=1b | gzip -cq > my.sda.raw.gz
the tool can handle different files in a struct array, like:
Code:
enum FilesOpenStatusValue {
FileIsClosed = 0,
FileIsOpen,
[code]....
Is there a better way of getting the file name of the redirected file, (respecting the fact that there may not always exist such a thing as a file name for a redirection pipe).
Should i work with inodes instead, and then take a completely different approach when porting to non-unix platforms? Why isn't there a system call like get_filename(stdin); ?
If you have any input on this, or some questions, then please don't hesitate to post in this thread. To add some offtopic to the thread - Here is a performance tip: When doing data shuffling on streams one should avoid just using some arbitrary record length, (like 512 bytes). Use stat() to get the recommended block size in stat.st_blksize and use copy buffers of that size to get optimal throughput in your programs.
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Sep 7, 2010
I'm writing a script to execute bash commands in the PHP CLI. I would like to suppress errors from bash and write my own error message if an error occurs. So far I have this (assuming log.txt doesn't exist!):
Code:
tac log.txt 2>/dev/null
Which works as expected, tac kicks up an error but the error is suppressed, but when I use this:
Code:
tac < log.txt 2>/dev/null
I get:
Code:
bash: log.txt: No such file or directory
The tac error is suppressed but bash still gives me a dirty error.
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Oct 27, 2010
So I have been doing some RAID 5 performance testing and am getting some bad write performance when configuring the RAID with an even number of drives. I'm running kernel 2.6.30 with software based RAID 5. This seems rather odd and doesn't make much since to me. For RAID 0 my performance consistently increases as I add more drives, but this is not the case for RAID 5. Does anyone know why I might be seeing lower performance when constructing my RAID 5 with 4 or 6 drives rather than 3 or 5?
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Feb 18, 2011
i want to write shell script that give a number between 1-3444 from user and if user enter out of range number give error e.g number must between
read -p "plz Enter Number " p
while [ $p != [1-9] -o $p != [1-9][0-9] -o $p != [1-3][0-4][0-4][0-4] ]
do
read -p "plz Enter Valid Number" p
done
but this have an error in while statement ! two many argument
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Jan 8, 2010
Code:
#!/usr/bin/perl
use 5.10.0;
use strict;
use warnings;
use Net::Ping;
[code]....
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Apr 13, 2011
I'm trying to write a bash script with a for loop that will perform two tasks a number of times depending on the number the user enters at the start. Here is what I got so far. It works fine the first time but then it just exits with no error msgs. The problem is in the way I have written the loop command. I have searched the web for examples to find out what I'm doing wrong with no luck.
#!/bin/bash
declare -i Num=1
declare -i Strnum=8
[code]....
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Oct 8, 2010
I need to write shell script which can take number of files and count total rows from all CSVs and display total number of rows counted in all files. Is there any possibility of doing that using shell script and if yes then how.
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Feb 1, 2010
I have some code that opens a directory and reads in the names of files which are e.g. 0001, 0002, 0003 up to 9999I need to get all these numbers and then generate a new number that is not one of these numbers already.here is my code to check the files in the directory
DIR *d;
struct dirent *dir;
int i = 0;
[code]....
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Jul 7, 2011
But what is the easiest way to figure out the Unicode number of a character when you already have the character?
For instance, I pasted this character here from a PDF:
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Apr 13, 2011
Anybody knows How can I get the number of cores of a machine?I know that I can use POPEN and get the stream of this:
Code:
grep -i 'processor' /proc/cpuinfo | wc -l
But, I think that a simple method to do this.
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Mar 4, 2011
i want to generate random number in c programming from -1 to 1
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Aug 6, 2010
1) I need to search a field value to check for exact 0. If the number is 0, it should throw error.
The line to be searched looks like as below. "Output Rows [1], Affected Rows [1], Applied Rows [1], Rejected Rows [0]"
Here I have to search whether the affected rows is 0. But the code below picks up other values also (lie 10, 20.. etc). How do we write to get an exact match for 0? Code: affected=`echo ${line} | cut -f6 -d" " `
affectedcount='echo ${affected} |grep 0 ` 2) Also, I need to check whether the rejected rows > 0
Code: rejected=`echo ${line} | cut -f12 -d" " `
rejectedcount='echo {rejected} |grep [1-9]`
3)Can we combine these two statements in a better way to get the desired results?
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Apr 30, 2011
I've created (as a homework) to create as many folders as told but I still need to check if the variable is a number or not :
Code: #!/bin/sh
echo "Veuillez saisir un nombre"; read nmbr
nmbrf=$nmbr
while [ $nmbrf -gt 0 ]
do mkdir -p "foo$nmbrf"
nmbrf=`expr $nmbrf - 1`
echo "$nmbrf"
how do I check that nmbr is a number or something else?
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Jan 10, 2011
I try to get the absolute value of a floating number but i could not until now. I am using bash script btw.lets say A is a floating number:A=-0.125
Code:
absA=$(echo '$A' | nawk '{print ($1>=0)? $1:0-$1}')
the above code gives absA=0, whereas
[code]....
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Jul 7, 2011
I'm having a hard time trying to get the number of digits in a uint64_t variable. The reason I'm using this is I want to make sure I get x amount of digits inside of a variable before I use it, but since the higher the digits, the better the program is.I currently use the following code, and it works, but my loop will never exit because the length is always 0:
Code:
/**
* numbdigits()
* number: The number to evaluate [in]
*
* Returns the number of digits found in a number.
[code]....
getrand() returns a uint64_t as well (and works). The only way the while() loop ends without my intervention is if I do curd += numdigits(val) instead...but, that gives a false value as well.
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Jan 27, 2011
I have a char*[] array:
Code:
char* myarray[] = {"Hello", "there!", "LQ"};
and I wish to use/ write a function to find the number of elements in myarray (in this case, its 3).
*equivalent of .NET's array.size() that returns number of elements in array
How do I achieve it?
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Apr 23, 2009
I have a text file that contains the following string of numbers and letters:
Code:
Mean track length: 3.45 +/- 1.23 mm
or
Code:
Mean track length: 22.45 +/- 12.23 mm
In the first example, I would like to grab only 3.45 and write it into a new file. Then I would like to grab only 1.23 and write it into another file.
I have 80,000 files to do and those numbers can be different every time.
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May 9, 2010
I want to be able to run a piece of AWK code on a record specified by number, not by a regex.
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Jun 16, 2010
User submits a ms word file, and the php can recognize the number of words? Is it only possible for ms win server?
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May 10, 2011
How can I know what number descriptor is used by my usb device indicate via libusb_device_handle structure ? I can't find declaration of libusb_device_handle structure. I need this information to use poll() function where I need decripttion number of device.
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May 10, 2011
How can I know what number descriptor is used by my usb device indicate via libusb_device_handle structure ? I can't find declaration of libusb_device_handle structure. I need this information to use poll() function where I need decripttion number of device.
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