I am new to shell and I'd like to learn, however, it seems a bit too complex to understand:
find . \( -name *.rar \) | xargs -I {} unrar x {}
Can you please explain step by step what is does. I know that it goes into folders and finds all the .rar files that it finds and then it chains the files that it finds into the second part of the command using | symbol.
However, I do not understand the xargs -I {} unrar x {} part, and {} command in particular. I know that unrar extracts the archive.
The {} is a placeholder, replaced with a filename in the generated command.
However, don't use this code; it will behave badly with rar archives having unusual names, or if there are any files matching *.rar in the current directory (as opposed to subdirectories). Consider instead:
find . -name '*.rar' -exec unrar x '{}' ';'
...or, if you really want to use xargs:
find . -name '*.rar' -print0 | xargs -n 1 -0 unrar x
Related
I would like to rename several files picked by find in some directory, then use xargs and mv to rename the files, with parameter expansion. However, it did not work...
example:
mkdir test
touch abc.txt
touch def.txt
find . -type f -print0 | \
xargs -I {} -n 1 -0 mv {} "${{}/.txt/.tx}"
Result:
bad substitution
[1] 134 broken pipe find . -type f -print0
Working Solution:
for i in ./*.txt ; do mv "$i" "${i/.txt/.tx}" ; done
Although I finally got a way to fix the problem, I still want to know why the first find + xargs way doesn't work, since I don't think the second way is very general for similar tasks.
Thanks!
Remember that shell variable substitution happens before your command runs. So when you run:
find . -type f -print0 | \
xargs -I {} -n 1 -0 mv {} "${{}/.txt/.tx}"
The shell tries to expan that ${...} construct before xargs even
runs...and since that contents of that expression aren't a valid shell variable reference, you get an error. A better solution would be to use the rename command:
find . -type f -print0 | \
xargs -I {} -0 rename .txt .tx {}
And since rename can operate on multiple files, you can simplify
that to:
find . -type f -print0 | \
xargs -0 rename .txt .tx
Until now when I want to gather files from a list I have been using a list that contains full paths and using:
cat pathlist.txt | xargs -I % cp % folder
However, I would like be able to recursively search through a folder and it's subfolders and copy all files that are in a plain text list of just filenames (not full paths).
How would I go about doing this?
Thanks!
Assuming your list of file names contains bare file names, as would be suitable for passing as an argument to find -name, you can do just that.
sed 's/^/-name /;1!s/^/-o /' pathlist.txt |
xargs -I % find folders to search -type f \( % \) -exec cp -t folder \+
If your cp doesn't support the -t option for specifying the destination folder before the sources, or your find doesn't support -exec ... \+ you will need to adapt this.
Just to explain what's going on here, the input
test.txt
radish.avi
:
is being interpolated into
find folders to search -type f \( -name test.txt -o -name radish.avi \
-o name : \) -exec cp -t folder \+
Try something like
find folder_to_search -type f | grep -f pattern_file | xargs -I % cp % folder
Use the find command.
while read line
do
find /path/to/search/for -type f -name "$line" -exec cp -R {} /path/to/copy/to \;
done <plain_text_file_containing_file_names
Assumption:
The files in the list have standard names without, say newlines or special characters in them.
Note:
If the files in the list have non-standard filenames, tt will be different ballgame. For more information see find manpage and look for -print0. In short you should be operating with null terminated strings then.
Im learning unix programming , i want to find all files whose size is greater than 1M an print them into a file.
here is my code
find. -size +1M -print0 | xargs -I -O '{}' mv '{}' files
all sites i have found refer to this one as right one , but it does not work . currently im working on ubuntu
You mis-copied/mis-typed the commend from wherever you found it.
The first {} is the argument to -I.
-O is not an argument to xargs you meant -0 (to go with -print0).
You missed the space between find and . (the current directory).
Which would get you:
find . -size +1M -print0 | xargs -0 -I '{}' mv '{}' files
That being said you don't need xargs here at all since find can execute commands directly.
find . -size +1M -exec mv {} files \+
And it is generally a good idea to test a complicated find command before you run it.
Using find . -size +1M by itself will just print the matching files.
Using
find . -size +1M -ok mv {} files \+
will cause find to prompt you before each execution of the command.
I am trying to remove all empty files that are older than 2 days. Also I am ignoring hidden files, starting with dot. I am doing it with this code:
find /u01/ -type f -size 0 -print -mtime +2 | grep -v "/\\." | xargs rm
It works fine until there are spaces in the name of the file. How could I make my code ignore them?
OS is Solaris.
Option 1
Install GNU find and GNU xargs in an appropriate location (not /usr/bin) and use:
find /u01/ -type f -size 0 -mtime +2 -name '[!.]*' -print0 | xargs -0 rm
(Note that I removed (what I think is) a stray -print from your find options. The options shown removes empty files modified more than 2 days ago where the name does not start with a ., which is the condition that your original grep seemed to deal with.)
Option 2
The problem is primarily that xargs is defined to split its input at spaces. An alternative is to write your own xargs surrogate that behaves sensibly with spaces in names; I've done that. You then only run into problems if the file names contain newlines — which the file system allows. Using a NUL ('\0') terminator is guaranteed safe; it is the only character that can't appear in a path name (which is why GNU chose to use it with -print0 etc).
Option 3
A final better option is perhaps:
find /u01/ -type f -size 0 -mtime +2 -name '[!.]*' -exec rm {} \;
This avoids using xargs at all and handles all file names (path names) correctly — at the cost of executing rm once for each file found. That's not too painful if you're only dealing with a few files on each run.
POSIX 2008 introduces the notation + in place of the \; and then behaves rather like xargs, collecting as many arguments as will conveniently fit in the space it allocates for the command line before running the command:
find /u01/ -type f -size 0 -mtime +2 -name '[!.]*' -exec rm {} +
The versions of Solaris I've worked on do not support that notation, but I know I work on antique versions of Solaris. GNU find does support the + marker and therefore renders the -print0 and xargs -0 workaround unnecessary.
So basically, I have a folder with a bunch of subfolders all with over 100 files in them. I want to take all of the mp3 files (really generic extension since I'll have to do this with jpg, etc.) and move them to a new folder in the original directory. So basically the file structure looks like this:
/.../dir/recup1/file1.mp3
/.../dir/recup2/file2.mp3
... etc.
and I want it to look like this:
/.../dir/music/file1.mp3
/.../dir/music/file2.mp3
... etc.
I figured I would use a bash script that looked along these lines:
#!/bin/bash
STR=`find ./ -type f -name \*.mp3`
FILES=(echo $STR | tr ".mp3 " "\n")
for x in $FILES
do
echo "> [$x]"
done
I just have it echo for now, but eventually I would want to use mv to get it to the correct folder. Obviously this doesn't work though because tr sees each character as a delimiter, so if you guys have a better idea I'd appreciate it.
(FYI, I'm running netbook Ubuntu, so if there's a GUI way akin to Windows' search, I would not be against using it)
If the music folder exists then the following should work -
find /path/to/search -type f -iname "*.mp3" -exec mv {} path/to/music \;
A -exec command must be terminated with a ; (so you usually need to type \; or ';' to avoid interpretion by the shell) or a +. The difference is that with ;, the command is called once per file, with +, it is called just as few times as possible (usually once, but there is a maximum length for a command line, so it might be split up) with all filenames.
You can do it like this:
find /some/dir -type f -iname '*.mp3' -exec mv \{\} /where/to/move/ \;
The \{\} part will be replaced by the found file name/path. The \; part sets the end for the -exec part, it can't be left out.
If you want to print what was found, just add a -print flag like:
find /some/dir -type f -iname '*.mp3' -print -exec mv \{\} /where/to/move/ \;
HTH