we all know that in linux directory is a special file containing the file name and the inode number of constituent files. I want to read the contents of this directory file using standard command line utility.
cat . gives an error that I cannot open a directory.
However, apparently vim can understand the content of this file using readdir probably. It displays the contents of the directory file in a formatted manner. I want the raw contents of the file. How is this possible ??
As far as I can tell, it cannot be done. I was pretty sure dd would do it, and then I found the following
‘directory’
Fail unless the file is a directory. Most operating systems do not allow I/O to a directory, so this flag has limited utility.
http://www.gnu.org/software/coreutils/manual/html_node/dd-invocation.html
So I think you have your answer there. dd supports it, as do probably a number of other utilities, but that doesn't mean linux allows it.
I think stat might be the command you're looking for.
Related
I have did search and people say that I must use
sudo sh -c ’echo 1 > /proc/sys/kernel/randomize_va_space to edit this file. Can someone explain to me why?
When I use vim with root to edit this file and save it shows an error: "/proc/sys/kernel/randomize_va_space" E667: Fsync failed
The files in /proc are not regular files. They are in fact kernel variables exposed through filesystem for easier access. Because of that, they don't support all functions of "normal" files, namely, fsync.
The text editor doesn't know that it's dealing with a special file and tries to use some unsupported function. On the other hand, echo ... > file works because it does not use fsync function.
fsync is a function that tells the OS to write any pending changes from file to disk.
Basically I have .bz2.gz.bz2 file which on extraction gives a .bz2.gz file and on again extraction gives .bz2 file. In this .bz2 file, is my txt file which I want to search on using grep command. I have searched for this but I got bzgrep command which will only search in bz2 file and not the corresponding .gz.bz2 file and give me no results.
Is there a command in unix system which will recursively search in a zipped archive for zipped archive and return results only when it finds the txt file inside it?
P.S: the txt file may be deep in the archive to level 10 max. I want the command to recursively find the txt file and search for the required string. And there will be no other than an archive inside the archive until the txt file level.
I'm not sure I fully understand but maybe this will help:
for i in /path/to/each/*.tar.bz2; do
tar -xvjf "$i" -C /path/to/save/in
rm $i
done
extract all `tar.bz2` and save them in directory then remove the `.bz2`
Thnx for sharing your question.
There are a couple of strange things with it though:
It makes no sense to have a .bz2.gz.bz2 file, so have you created this file yourself? If so, I'd advise you to reconsider doing so in that manner.
Also, you mention there is a .bz2 that would apparently contain different archives, but a .bz2 can only contain one single file by design. So if it contains archives it is probably a .tar.bz2 file in which the tar-file holds the actual archives.
In answer to your question, why can't you write a simple shell script that will unpack your .bz2.gz.bz2 into a .bz2.gz and then into a .bz2 file and then execute your bzgrep command on that file?
I do not understand where it is exactly that you seem to get stuck..
I have a problem with writing the output of a program to a different directory when I loop different files as variables as inputs. I run this in the command line. The problem is that I do not know how to "tell" the program to put the output with a changed filename into another directory than the input directory.
Here is the command, although it is a bioinformatic tool which requires specific input file formats. I am sorry that I could not give a better example. Nonetheless, the program is called computeMatrix in a software-tool box called deeptools2.
command:
for f in ~/my/path/*spc_files*; do computeMatrix reference-point--referencePoint center --regionsFileName /target/region.bed --binSize 500 --scoreFileName "$f" **--outFileName "$f.matrix"** ; done \
So far, I tried to use the command basename to just get the filename and then change the directory before that. However I could not figure out:
if this is combinable
what is the correct order of the commands (e.g.:
outputFile='basename"$f"', "~/new/targetDir/'basename$f'")
Probably there are other options to solve the problem which I could not think of/ find.
As per the answer to this question, I am trying to backup a file by renaming it, before I replace it with a new, modified file with the old name.
As per the comments and the documentation here, I am using the following line of code:
File.rename(File.basename(modRaw), File.basename(modRaw)+'.bak')
However, when I do so, I get the following error at runtime:
The program then aborts. (leatherReplacer.rb is the name of my program, and line 88 is the above line of code)
How do I allow my program to rename the files it needs to to run successfully?
Windows has some special rules regarding permissions. The important one at work here, is that the OS prevents moving or renaming a file while the file is open.
Depending on the nature of your code (in size and scope) and the importance of the file you're trying to back up, it may be unfeasible or otherwise not worthwhile to refactor the code in such a way as to make backups possible.
You probably don't want to be calling File.basename in there, that strips off the directory:
Returns the last component of the filename given in *file_name*, which must be formed using forward slashes ("/") regardless of the separator used on the local file system.
So, if modRaw is /where/is/pancakes.house, then you're saying:
File.rename('pancakes.house', 'pancakes.house.bak')
But pancakes.house probably isn't in the script's current directory. Try without the File.basename calls:
File.rename(modRaw, modRaw + '.bak')
If you are owner of that file, use File.chmod to set desired permissions.
I don't know much about ruby, but could you run it under command line/bash with admin privileges, such as "run as administrator" or "su root"?
According to Objectmix and ruby-forum, you should set it to 755 or +x, then perhaps chown to yourself.
try using full file path e.t
File.rename('c:\pancakes.house', 'c:\pancakes.house.bak')
in win7 i encounter same problem
I was looking for a way to create hard links under Windows and I found this page: http://technet.microsoft.com/en-us/library/cc788097.aspx
To try it out, I created a file (1.txt) on the root of my C: drive with 100 lines of the following content:
C:\1.txt (2.598 bytes):
test test test test test
Then I open the command prompt and typed:
fsutil hardlink create C:\2.txt C:\1.txt
Success, 2.txt was created but when I go to see it's size it has exactly 2.598 bytes and also noticed some strange behaviours (as far as my understanding of hard links goes):
If I delete 2.txt (the hard linked file) 1.txt is not deleted, and vice-versa.
If I open 2.txt after I delete 1.txt (the original file) the content is still the same.
How does the fsutil hardlink create command differs from the copy command? And how can I create a true hard link under Windows?
I'm using Windows XP SP 3, and my file system is NTFS.
That's exactly the behavior that supposed to happen. Are you sure you understand how hard links work? Hard links are really just multiple entries in the file system that refer to the exact same file. If you create a hard link to a file and modify one of the instances of the file, the other file will show up with your changes because they both refer to the same blocks of data on disk.
When you delete one of the hard links, you're really just deleting one of the file system entries referring to that file. The file doesn't get deleted until you delete all of its hard links (including the original one). After you delete 1.txt, 2.txt still exists and refers to the same file that was originally there, only now there is only a single file system entry referring to that file (namely, 2.txt). 2.txt is that file.
How does the fsutil hardlink create
command differs from the copy command?
And how can I create a true hard link
under Windows?
After creating the hardlinked file, try editing either. You will discover that the changes are reflected in both files.
Try creating a hard-link of a very large file (say a video or disk-image). Notice that the available space on the disk has not changed (or not changed by more than a few bytes, if additional metadata had to be written to disk to reflect the new dir entry).
That is a true hard link. In UNIX (I'm not familiar with the Windows variant) a file is just a set of data on the disk (simplistically). It's the directory entry itself that gives that file a name.
When you have two directory entries pointing at the same underlying file, deleting one of them does not delete the file unless it's the last directory entry attached to it (and the file is not still open by a process, but that's a different matter).