What does the following Shell program do ??: () { :| : &} ; :Warning: My computer got hung when i tried to execute this.Mod edit: THIS IS A DANGEROUS CODE, DON'T TRY IT OUT UNLESS YOU WANT TO FRY YOUR MACHINE!
I am trying to process a column separated data file, with a few bash command. For example, I have
Code:
file1 aaaa yes file2 aaaa no file3 bbbb yes
Let say I want to create new file with the output of first column and do something else with the output of 3rd column. Of course there are many ways to process this data file, but I wish to know by using awk, how could I do it. I'm trying:
Code:
awk '{system("touch $1")}' datafile
but the shell command will not able to get the awk '$1' output. How do I get this done ? And for another question, if the data file contains the variable name of a shell variable, how could I make use of it during a awk output ? For example I have a datafile1:
Code:
server1 yes server2 no
And in another server declaration data file, I got this datafile2:
Code:
server1=xxx1 server2=yyy1
And in my awk script, I want to achieve something like (the syntax is definitely wrong, just to demonstrate what I assume it will like):
I am trying to grep multiple numbers from file, grep does have the -f option for that.
Code: grep -f <`seq 500 520` /etc/passwd I know this could be done with
Code: for i in `seq 500 520`; do grep "$i" /etc/passwd; done But my question is fare more behind this example. It is possible to redirect one command output which will be treat as a content of file for another command ?
I'm having trouble with a bash script. I have something like this:export VAR=`command`The problem is that "command" can return this: "** NONE **". bash will then replace each of the * by the list of files in the current directory.I want the output to be uninterpreted (i.e. VAR should contain "** NONE **", not "list of files list of files NONE list of files list of files"). It shouldn't be hard but I am unable to figure it out, and I'm not sure how to phrase the problem,
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 am trying to automate an svnadmin dump command for a backup script, and I want to do something like this:
find /var/svn/* ( ! -name dir -prune ) -type d -exec svnadmin dump {} > {}.svn ;
This seems to work, in that it looks through each svn repository in /var/svn, and runs svnadmin dump on it.
However, the second {} in the exec command doesn't get substituted for the name of the directory being processed. It basically just results a single file named {}.svn.
I suspect that this is because the shell interprets > to end the find command, and it tries redirecting stdout from that command to the file named {}.svn.
I want to scan a particular directory recursively and run a particular command with each file as input. For this I am using "find /dir/path". I dont want to write any long script containing loop on the output of "find". I want a single command which will allow me to run a command on each file of the "find" command output.
I'm having problems with Tomboy. I have a few hundred note files and I need to go through all of them and replace all instances of "<link:broken>a</link:broken>" with "a". Is there a bash command I can use to do this?
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.
We make everyday a DB Mysql backup on Linux redhat Enterprise. We are using a bash shell script (and putting it in the crontab) to execute it automatically everyday. We added a line to this script telling, once the backup has completed, to find old backup files (stored on hard disk after each backup) older than x days to remove them. We use the find command (search for file type) with the mtime option and in combination with rm command. Everything runs ok but we also want to add some new code to the same line: If find command cannot find anything or fails, for example if it cannot delete file or fails, send the error message (standard error output) to an error file (like error000001 and increasing) and mail the errorxxxx file to an email address for example to admin@companyname.com. What would be the code for this issue to add it to our find command in the same bash shell script??
I use command "find" in my bash script: if the filename exist command find work quiet, and if the filename not exist I see the message "find: /tmp/filename: No such file or directory". My problem is following, i want to have in my script something like this:
find "/tmp/filename" -type f -delete | "if no_any_errors execute command1" , if file_not_found execute command2"
I create a bash script that writes another bash file. But in the generated bash file I want to write a bash command in the file and not executing it.Here's my bash file:
Code: #!/bin/bash cat > ~/generateGridmix2data.sh << END
I am using openSUSE 10.3.When I install software from tarball then to record time required I send output of date to beg.txt(when installation begins) and end.txt (when installation finishes).How can I append output of date to a file so I don't need two files?
I want to run gsettings list-schemas (which return a list of about 100 names separated by spaces)and somehow direct each name one at a time as the input to this command:gsettings list-recursivelyI've tried it with awk, and standard | piping and also as a string variable strvar=$(gsettings list-schemas) and using the $strvar as the input butam missing something in between I'm sure like for - while or proper syntax of awk etc
I want to use the output of a previous command as a parameter to another command. For example: to know where "nice" is stored i typed: which nice output: /usr/bin/nice now the second command i typed is: ls -l /usr/bin/nice Is there a way to have a single command like: ls -l which nice ?
I'm still trying to find out if my coby mp3 player will actually play mtv video files as is advertised.
ffmpeg -formats does list mtv but the only command I really ever used was one to convert a vid to an mp3 so I tried Code: ffmpeg -i test.mp4 -acodec copy output.mtv it returns Code: Unable to find a suitable output format for 'output.mtv' I can't find any mtv files online for purchase or free for that matter, so I know this is all pretty obscure but shouldn't there be a way to convert them since ffmpeg lists mtv format?
I just recently learned about the wonderful little lpr command- and using man -t (bash command) to beautifully print man pages for reference- but is there a way to print both sides of the paper using a printer so equipped?
Bash's command history is great, especially it is useful when adding the history -a command to the COMMAND_PROMPT.However, I'm wondering if there is a way to log the commands to a file as soon as the Return key is pressed, e.g. before starting the command and not on completion of the command (using the COMMAND_PROMPT option would save the command once the prompt is there again).
I read about auditing programs like snoopy and session recorder like script but I thought they're already too complex for the simple question I have. I guess that deactivating that script logs all the output of the command would lead already in the right direction but isn't there a quicker way to solve that probelm?
I have a script that generates a bunch of output, including the expansions details provided by: set -v -xI am trying to pipe everything that is displayed to a file, in addition to displaying it on the screen. I've managed to get stderr and stdout into the file, but the expansions are only printed to the screen. Here is what I have so far:sudo -u <user> source my_job.sh |tee my_log.txt 2>&1
