General :: Writing To The STDIN Of A Shell?
Jul 28, 2010
I am trying to write input to a shell and get the shell to parse the input that I am writing to it as if a user was typing in commands.
Thus far I have tried echoing some text into the shell's FD for STDIN in /proc/<pid>/fd Whilst this displays the text that I echo, the shell that I am writing to never tries to execute the command that I pass to STDIN. What is the difference between a shell taking STDIN from the user and data written to STDIN by another process e.g. echo ? It appears I am missing something fundamental.
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Aug 10, 2010
I am about to write my first shell script for backing up my server.
These are the steps I have identified so far.
Copy files to be backed up to /srv/backup/ run mysqldump and copy the file to srv/backup/databases run duplicity to backup /srv/backup/* to another folder on my machine
I am writing a bash shell scrip that will be run everyday, and will carry out the three tasks mentioned above.
Note: point 3 (backing up to a local folder) is only a temporary measure - to allow me to understand what I'm doing, since all the tools I am using, are new to me. Once I can backup and restore correctly, I will use duplicity to compress and encrypt the files and upload them offsite.
If my understanding of duplicity is correct (according to the documentation here), the first time I run the script, a FULL backup will be done. Every subsequent backup will then be incremental. I will then force a FULL back on say a weekend.
First things first though - I have a few questions:
I would like to use backup rotation for the 'scheme' described above - I would like some recommendations on what kind/type of rotation to use. Once I have implemented the backup rotation, how can I restore from a particular day back in time (assuming the backup exists of course). ?
I am running Ubuntu 10.0.4
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Feb 6, 2011
I want to perform an action with a shell script and then log the event in a file in /var/log. However, I keep getting permission denied error messages.
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Mar 26, 2010
I need help creating a script that makes a log file in wich to save information about every user that uses the ftp command (information like username and date) and the server to wich he is trying to connect.
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Jan 10, 2011
I want to run gallist pkge from iraf for several times.. The step for running that
is:>xgterm &
>ecl &
ecl>noao
noao>artdata
artdata>epar gallist (I set some parameter) then by writing gallist iraf terminal the pkge is run:
artdata>gallist
I want this pkge is run for 1000 time and all output result are collected in only one file.
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Jan 5, 2011
I have been trying to write a simple snip of bash shell code to import from 1 to 100 records into a Bash array.
I have a CSV file that is structured like:
record1,item1,item2,item3,item4
record2,item1,item2,item3,item4
record3,item1,item2,item3,item4
record4,item1,item2,item3,item4
And would like to get this data into corresponding arrays as such:
$record1[item1-4]
$record2[item1-4]
$record3[item1-4]
$record4[item1-4]
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Mar 22, 2010
I want to write a single shell script that allows me to, once executed from a panel launcher, change the image preview setting between "local files only" and never. Right now i have two tiny scripts, one for local files only and another one for never, that is:
[Code]...
and the other says string "local_only". But that means i need to have two launchers, because i don't know how to write the condition <<when set to never, change it to local only. And is it possible to make a script that also changes the launcher's icon when the preview config is set to one or the other value? That way i'd know what it is set to just by looking at it. It would act as a diagnostic and therapeutic tool XD
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Oct 7, 2009
I'm new to UNIX scripting; I�m stuck with the following I have an Oracle SQL script that takes three parameters
1- File Name
2- File Path
3- File creation date
Under UNIX I have a folder where files will be placed frequently and I need to upload those files to Oracle, what I need is a UNIX script that can do the following
Loop through Directory "/home/applmgr/snktmp"
Picks only files
Pass the file name to parameter &1
[code]....
Is the above possible? I already knows how to call the Oracle Script from UNIX Im only stuck on writing the UNIX part where it List the files attribute(name,path,date) and store them to parameters ,Looping until the last file in the directory If the above is not possible,then how can I create the below from the command line
Filename{concatenation Mark}filePath{concatenation Mark}creationdate
Filename{concatenation Mark}filePath{concatenation Mark}creationdate
Filename{concatenation Mark}filePath{concatenation Mark}creationdate
Filename{concatenation Mark}filePath{concatenation Mark}creationdate
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Sep 26, 2010
I execute an application from a script file and redirect stdin to it from here-doc like this:
my_cli << HERE_DOC
enable
configure
10
exit
exit
HERE_DOC
This works as expected, but I don't see neither the input nor the app output. The application is an interactive prompt written in C. When I interact manually with it, I see the prompt itself and responses to my input, but when I execute the aforementioned script I see nothing. I would like it to print the input and the output as if a real user was typing. Do you know how to achieve that?
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Apr 28, 2011
I have the following bash script:
#do some time consuming task here read -p "Give me some input: " input
Now as you might've guessed, if users press some random keys during the "time consuming task," they're read into input as well. how do I clear stdin (or at least ignore it) before I issue the read command?
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Jun 28, 2010
Is it possible to redirect stdout and stderr from one terminal say /dev/pts/2 to another /dev/pts/3?
I tried the following:
Code:
/dev/pts/2 2>&1 /dev/pts/3&
Then when I run a command the process stops.
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Nov 22, 2010
I need to achieve a particular effect using bash's redirection facilities.I know that I can redirect a file to some program's standard input:[user@host]$ application < file.txtThe thing is, I'd like to know can I regain control of this program's input after the file content's have been passed to it. In other words, I'd like to run a command similar to the above, and then, instead of the termination of the application, I'd want it to wait for further commands from standard input (keyboard).
As I write this question, it occured to me that I could probably write another application (or a script), that would at first write some data to standard output and then act as echo, like:[user@host]$ stdin_proxy.sh | applicationWould it work, and is there any better way to do so? There are a bunch of Googleable tutorials covering this issue, but they all amount to one advice - "reopen the stdin after the file contents have been read".
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Mar 28, 2011
when iam opening my dec_backup folder the folling error is appering :
the error is gzip :stdin:input /output error
/bin /gstar :unexpected EOF in archive
/bin /gstar: error is not recoverable :exesting now
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Nov 20, 2009
i'm trying to redirect the output of a command to the input of the next command. not sure if i'm going about this the right way. an easy method would be just to store the output of the previous command in a file and redirect input to read that file, but i'm curious to see if this can be done without writing to any files.
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Jun 15, 2011
MACHINE: HP Proliant DL260G5OS: SLES 11 SP1kernel: Linux xserver 2.6.32.12-0.7-default #1 SMP 2010-05-20 11:14:20 +0200 x86_64 x86_64 x86_64 GNU/LinuxIt is used as remote xserver in a LAN.I have configured /usr/lib/restricted/bin/.rbashrc with some environment variables but when the users logon in the system finally is executed $HOME/.bashrc and some environment vars are overwritten.
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Apr 27, 2011
I would like know when it is necessary or advisable to write a shell script instead of shell function ?
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Mar 7, 2011
i've tryed to get rid of the ugly plymouth splash screen and this outpout at boot now:
stdin: error 0
and so on... It also appears in my /var/log/boot.log and /var/log/casper.log. But the OS works, just like before. I would like to know how can i get rid of this error. Or how can i hide it? Can i redirect the output to dev null at boot time?
Here is boot.log
Code:
stdin: error 0
Generating locales...
sl_SI.UTF-8... up-to-date
Generation complete.
[Code]....
Because it is really annoying to see an "error" when your computer boots, even if it is not really an error
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Jan 18, 2011
I am wondering if I can open a shell or new terminal thing from within the terminal in a unix/linux enviroment. Particularly a commandline only one where there is no GUI. Is this doable? how do I do it?
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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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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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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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Oct 19, 2010
causes a 'p' to appear in tty7 but not the program running in 7 to react as though a 'p' had been pressed.
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Mar 25, 2010
My VPN is behaving funny sometimes, and I have to restart it often.I wanted to write a script which does that for me.It doesn't have to be anything fancy, just a shortcut for the commands I have to type into the terminal. More specifically: it will look at the running processes.If it finds a running vpnc process, it will kill it. Then it will start vpnc.I've written bash scripts of similar complexity,but now I don't have a bash,only an ash. Until now, the only difference I noticed is that there are much less commands available, but then, I don't use it very often.So I have some questions.
Is writing ash scripts different than writing bash scripts?
Is there something specific to consider when doing it?
When the script is ready, how can I deploy it? For bash, I just put the executable file under /usr/lib and run it by typing the file name into the command line, will this work with ash?
Are there any special pitfalls to watch out for in the script I want to write? I think that the killing process part may get hairy, if I write something that kills the wrong process, but even then running the script shouldn't break anything permanently, right?
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Mar 3, 2011
i am having a the following line in a file
<property name="connection.password"></property>
i have to give password in this line, like this
<property name="connection.password">XXXXXX</property>
Is this possible to acheive this using sed command
Beause i have to do this for n number files. so if i have option in sed for this the i will be doing this using script.
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Jun 18, 2011
I have two Debian machines running Squeeze x86 and x86_64.
I am having difficulties to untar a file in x86_64, although it is working in x86.
I made sure file is the same and the md5 match in both machines.
It seems like something special in x86_64 is causing it to fail.
See below:
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Jan 25, 2011
user@user-laptop:~$ sudo dd if=sd_backup of=/dev/sdd bs=4M conv=noerror,sync
205520896 bytes (206 MB) copied, 28.564 s, 7.2 MB/s
247463936 bytes (247 MB) copied, 57.1285 s, 4.3 MB/s
260046848 bytes (260 MB) copied, 73.2388 s, 3.6 MB/s
289406976 bytes (289 MB) copied, 104.121 s, 2.8 MB/s
[Code]....
How come dd gets slower after copying this 8GB file? What can I do about it?
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