find -name with and without xargs give different result - linux

I'd need to perform some operations on a lot of files in a lot of dirs, say checking whether they are password protected or not.
I've created a bash script (fileproc.sh) and I'd want to check if it works so I did a silly thing just to see if it works:
#!/bin/sh
echo 'File: ' + $1
Then if I run a simple
find . -name "*.zip" -type f
I have a long list of .zip files as expectd.
If I run
find . -name "*.zip" -type f -print0 | xargs ./fileproc.sh
I have only three files.
What am I doing wrong?
Thanks

xargs is used to run the command with more than one argument, see man xarg. It will append the lines printed by find to the command line until a system-dependent limit is reached.
$1 is just the first command line argument, you don't see the second and following arguments.
In your script try
echo 'File(s): ' "$#"

Related

find all files with certain extensions then execute

Why does running this command give me error message: No such file or directory ?
for i in `find ~/desktop -name '*.py'` ; do ./$i ; done
The complete error message makes it much more clear what the problem is:
bash: .//home/youruser/desktop/foo.py: No such file or directory
You can see that there is indeed no such file:
$ .//home/youruser/desktop/foo.py
bash: .//home/youruser/desktop/foo.py: No such file or directory
$ ls -l .//home/youruser/desktop/foo.py
ls: cannot access './/home/youruser/desktop/foo.py': No such file or directory
Here's instead how you can run a file /home/youruser/desktop/foo.py:
$ /home/youruser/desktop/foo.py
Hello World
So to run it in your loop, you can do:
for i in `find ~/desktop -name '*.py'` ; do $i ; done
Here's a better way of doing the same thing:
find ~/desktop -name '*.py' -exec {} \;
or with a shell loop:
find ~/desktop -name '*.py' -print0 | while IFS= read -d '' -r file; do "$file"; done
For an explanation of what ./ is and does, and why it makes no sense here, see this question
Try find and exec option. http://man7.org/linux/man-pages/man1/find.1.html
-exec command ;
Execute command; true if 0 status is returned. All following
arguments to find are taken to be arguments to the command
until an argument consisting of `;' is encountered. The
string `{}' is replaced by the current file name being
processed everywhere it occurs in the arguments to the
command, not just in arguments where it is alone, as in some
versions of find. Both of these constructions might need to
be escaped (with a `\') or quoted to protect them from
expansion by the shell. See the EXAMPLES section for examples
of the use of the -exec option. The specified command is run
once for each matched file. The command is executed in the
starting directory. There are unavoidable security problems
surrounding use of the -exec action; you should use the
-execdir option instead.
-exec command {} +
This variant of the -exec action runs the specified command on
the selected files, but the command line is built by appending
each selected file name at the end; the total number of
invocations of the command will be much less than the number
of matched files. The command line is built in much the same
way that xargs builds its command lines. Only one instance of
`{}' is allowed within the command, and (when find is being
invoked from a shell) it should be quoted (for example, '{}')
to protect it from interpretation by shells. The command is
executed in the starting directory. If any invocation with
the `+' form returns a non-zero value as exit status, then
find returns a non-zero exit status. If find encounters an
error, this can sometimes cause an immediate exit, so some
pending commands may not be run at all. This variant of -exec
always returns true.
The paths returned by the find statement will be absolute paths, like ~/desktop/program.py. If you put ./ in front of them, you get paths like ./~/desktop/ which don’t exist.
Replace ./$i with "$i" (the quotes to take care of file names with spaces etc.).
You should use $i and not ./$i
I was doing the same thing this exact moment. I wanted a script to find if there's any flac files in the directory and convert it to opus.
Here is my solution:
if test -n "$(find ./ -maxdepth 1 -name '*.flac' -print -quit)"
then
do this
else
do nothing
fi

Insert line into multi specified files

I want to insert a line into the start of multiple specified type files, which the files are located in current directory or the sub dir.
I know that using
find . -name "*.csv"
can help me to list the files I want to use for inserting.
and using
sed -i '1icolumn1,column2,column3' test.csv
can use to insert one line at the start of file,
but now I do NOT know how to pipe the filenames from "find" command to "sed" command.
Could anybody give me any suggestion?
Or is there any better solution to do this?
BTW, is it work to do this in one line command?
Try using xargs to pass output of find and command line arguments to next command, here sed
find . -type f -name '*.csv' -print0 | xargs -0 sed -i '1icolumn1,column2,column3'
Another option would be to use -exec option of find.
find . -type f -name '*.csv' -exec sed -i '1icolumn1,column2,column3' {} \;
Note : It has been observed that xargs is more efficient way and can handle multiple processes using -P option.
This way :
find . -type f -name "*.csv" -exec sed -i '1icolumn1,column2,column3' {} +
-exec do all the magic here. The relevant part of man find :
-exec command ;
Execute command; true if 0 status is returned. All following arguments
to find are taken to be arguments to the command until an argument consisting
of `;' is encountered. The string `{}' is replaced by the current file name
being processed everywhere it occurs in the arguments to the command, not just
in arguments where it is alone, as in some versions of find. Both of
these constructions might need to be escaped (with a `\') or quoted to protect
them from expansion by the shell. See the EXAMPLES section for examples of
the use of the -exec option. The specified command is run once for each
matched file. The command is executed in the starting directory. There
are unavoidable security problems surrounding use of the -exec action;
you should use the -execdir option instead

Find files in a dir, executing a command with execdir and redirecting

It seems like I am unable to find a direct answer to this question.
I appreciate your help.
I'm trying to find all files with a specific name in a directory, read the last 1000 lines of the file and copy it in to a new file in the same directory. As an example:
Find all files names xyz.log in the current directory, copy the last 1000 lines to file abc.log (which doesn't exist).
I tried to use the following command with no luck:
find . -name "xyz.log" -execdir tail -1000 {} > abc.log \;
The problem I'm having is that for all the files in the current directory, they all write to abc.log in the CURRENT directory and not in the directory where xyz.log resides. Clearly the find with execdir is first executed and then the output is redirected to abc.log.
Can you guys suggest a way to fix this? I appreciate any information/help.
EDIT- I tried find . -name "xyz.log" -execdir sh -c "tail -1000 {} > abc.log" \; as suggested by some of the friends, but it gives me this error: sh: ./tail: No such file or directory error message. Do you guys have any idea what the problem is?
Luckily the solution to use -printf is working fine.
The simplest way is this:
find . -name "xyz.log" -execdir sh -c 'tail -1000 "{}" >abc.log' \;
A more flexible alternative is to first print out the commands and then execute them all with sh:
find . -name "xyz.log" -printf 'tail -1000 "%p" >"%h/abc.log"\n' | sh
You can remove the | sh from the end when you're trying it out/debugging.
There is a bug in some versions of findutils (4.2 and 4.3, though it was fixed in some 4.2.x and 4.3.x versions) that cause execdir arguments that contain {} to be prefixed with ./ (instead of the prefix being applied only to {} it is applied to the whole quoted string). To work around this you can use:
find . -name "xyz.log" -execdir sh -c 'tail -1000 "$1" >abc.log' sh {} \;
sh -c 'script' arg0 arg1 runs the sh script with arg0, arg1, etc. passed to it. By convention, arg0 is the name of the executable (here, "sh"). From the script you can access the arguments using $0 (corresponding to "sh"), $1 (corresponding to find's expansion of {}), etc.
The redirect isn't passed into execdir, so abc.log shows up in the directory you run the command in. -execdir also doesn't like embedded redirects. but you can workaround the problem by passing -execdir a shell command with a redirect embedded, like this:
find . -name "xyz.log" -execdir sh -c '/usr/bin/tail -1000 {} > abc.log' \;
Much credit to this blog post (not mine):
http://www.microhowto.info/howto/act_on_all_files_in_a_directory_tree_using_find.html
Edit
I put the full path to tail in the command (assuming it's in /usr/bin on your system), since sh may load a .profile with a PATH that differs from your current shell.
Here's another non-find (well, sorta - it still uses find but doesn't try to shoehorn find into doing the whole thing):
while read f
do
d=$(dirname "${f}")
tail -n 1000 "${f}" > "${d}/abc.log"
done < <(find . -type f -name xyz.log -print)

Argument list too long error for rm, cp, mv commands

I have several hundred PDFs under a directory in UNIX. The names of the PDFs are really long (approx. 60 chars).
When I try to delete all PDFs together using the following command:
rm -f *.pdf
I get the following error:
/bin/rm: cannot execute [Argument list too long]
What is the solution to this error?
Does this error occur for mv and cp commands as well? If yes, how to solve for these commands?
The reason this occurs is because bash actually expands the asterisk to every matching file, producing a very long command line.
Try this:
find . -name "*.pdf" -print0 | xargs -0 rm
Warning: this is a recursive search and will find (and delete) files in subdirectories as well. Tack on -f to the rm command only if you are sure you don't want confirmation.
You can do the following to make the command non-recursive:
find . -maxdepth 1 -name "*.pdf" -print0 | xargs -0 rm
Another option is to use find's -delete flag:
find . -name "*.pdf" -delete
tl;dr
It's a kernel limitation on the size of the command line argument. Use a for loop instead.
Origin of problem
This is a system issue, related to execve and ARG_MAX constant. There is plenty of documentation about that (see man execve, debian's wiki, ARG_MAX details).
Basically, the expansion produce a command (with its parameters) that exceeds the ARG_MAX limit.
On kernel 2.6.23, the limit was set at 128 kB. This constant has been increased and you can get its value by executing:
getconf ARG_MAX
# 2097152 # on 3.5.0-40-generic
Solution: Using for Loop
Use a for loop as it's recommended on BashFAQ/095 and there is no limit except for RAM/memory space:
Dry run to ascertain it will delete what you expect:
for f in *.pdf; do echo rm "$f"; done
And execute it:
for f in *.pdf; do rm "$f"; done
Also this is a portable approach as glob have strong and consistant behavior among shells (part of POSIX spec).
Note: As noted by several comments, this is indeed slower but more maintainable as it can adapt more complex scenarios, e.g. where one want to do more than just one action.
Solution: Using find
If you insist, you can use find but really don't use xargs as it "is dangerous (broken, exploitable, etc.) when reading non-NUL-delimited input":
find . -maxdepth 1 -name '*.pdf' -delete
Using -maxdepth 1 ... -delete instead of -exec rm {} + allows find to simply execute the required system calls itself without using an external process, hence faster (thanks to #chepner comment).
References
I'm getting "Argument list too long". How can I process a large list in chunks? # wooledge
execve(2) - Linux man page (search for ARG_MAX) ;
Error: Argument list too long # Debian's wiki ;
Why do I get “/bin/sh: Argument list too long” when passing quoted arguments? # SuperUser
find has a -delete action:
find . -maxdepth 1 -name '*.pdf' -delete
Another answer is to force xargs to process the commands in batches. For instance to delete the files 100 at a time, cd into the directory and run this:
echo *.pdf | xargs -n 100 rm
If you’re trying to delete a very large number of files at one time (I deleted a directory with 485,000+ today), you will probably run into this error:
/bin/rm: Argument list too long.
The problem is that when you type something like rm -rf *, the * is replaced with a list of every matching file, like “rm -rf file1 file2 file3 file4” and so on. There is a relatively small buffer of memory allocated to storing this list of arguments and if it is filled up, the shell will not execute the program.
To get around this problem, a lot of people will use the find command to find every file and pass them one-by-one to the “rm” command like this:
find . -type f -exec rm -v {} \;
My problem is that I needed to delete 500,000 files and it was taking way too long.
I stumbled upon a much faster way of deleting files – the “find” command has a “-delete” flag built right in! Here’s what I ended up using:
find . -type f -delete
Using this method, I was deleting files at a rate of about 2000 files/second – much faster!
You can also show the filenames as you’re deleting them:
find . -type f -print -delete
…or even show how many files will be deleted, then time how long it takes to delete them:
root#devel# ls -1 | wc -l && time find . -type f -delete
100000
real 0m3.660s
user 0m0.036s
sys 0m0.552s
Or you can try:
find . -name '*.pdf' -exec rm -f {} \;
you can try this:
for f in *.pdf
do
rm "$f"
done
EDIT:
ThiefMaster comment suggest me not to disclose such dangerous practice to young shell's jedis, so I'll add a more "safer" version (for the sake of preserving things when someone has a "-rf . ..pdf" file)
echo "# Whooooo" > /tmp/dummy.sh
for f in '*.pdf'
do
echo "rm -i \"$f\""
done >> /tmp/dummy.sh
After running the above, just open the /tmp/dummy.sh file in your favorite editor and check every single line for dangerous filenames, commenting them out if found.
Then copy the dummy.sh script in your working dir and run it.
All this for security reasons.
For somone who doesn't have time.
Run the following command on terminal.
ulimit -S -s unlimited
Then perform cp/mv/rm operation.
I'm surprised there are no ulimit answers here. Every time I have this problem I end up here or here. I understand this solution has limitations but ulimit -s 65536 seems to often do the trick for me.
You could use a bash array:
files=(*.pdf)
for((I=0;I<${#files[#]};I+=1000)); do
rm -f "${files[#]:I:1000}"
done
This way it will erase in batches of 1000 files per step.
you can use this commend
find -name "*.pdf" -delete
The rm command has a limitation of files which you can remove simultaneous.
One possibility you can remove them using multiple times the rm command bases on your file patterns, like:
rm -f A*.pdf
rm -f B*.pdf
rm -f C*.pdf
...
rm -f *.pdf
You can also remove them through the find command:
find . -name "*.pdf" -exec rm {} \;
If they are filenames with spaces or special characters, use:
find -name "*.pdf" -delete
For files in current directory only:
find -maxdepth 1 -name '*.pdf' -delete
This sentence search all files in the current directory (-maxdepth 1) with extension pdf (-name '*.pdf'), and then, delete.
i was facing same problem while copying form source directory to destination
source directory had files ~3 lakcs
i used cp with option -r and it's worked for me
cp -r abc/ def/
it will copy all files from abc to def without giving warning of Argument list too long
Try this also If you wanna delete above 30/90 days (+) or else below 30/90(-) days files/folders then you can use the below ex commands
Ex: For 90days excludes above after 90days files/folders deletes, it means 91,92....100 days
find <path> -type f -mtime +90 -exec rm -rf {} \;
Ex: For only latest 30days files that you wanna delete then use the below command (-)
find <path> -type f -mtime -30 -exec rm -rf {} \;
If you wanna giz the files for more than 2 days files
find <path> -type f -mtime +2 -exec gzip {} \;
If you wanna see the files/folders only from past one month .
Ex:
find <path> -type f -mtime -30 -exec ls -lrt {} \;
Above 30days more only then list the files/folders
Ex:
find <path> -type f -mtime +30 -exec ls -lrt {} \;
find /opt/app/logs -type f -mtime +30 -exec ls -lrt {} \;
And another one:
cd /path/to/pdf
printf "%s\0" *.[Pp][Dd][Ff] | xargs -0 rm
printf is a shell builtin, and as far as I know it's always been as such. Now given that printf is not a shell command (but a builtin), it's not subject to "argument list too long ..." fatal error.
So we can safely use it with shell globbing patterns such as *.[Pp][Dd][Ff], then we pipe its output to remove (rm) command, through xargs, which makes sure it fits enough file names in the command line so as not to fail the rm command, which is a shell command.
The \0 in printf serves as a null separator for the file names wich are then processed by xargs command, using it (-0) as a separator, so rm does not fail when there are white spaces or other special characters in the file names.
Argument list too long
As this question title for cp, mv and rm, but answer stand mostly for rm.
Un*x commands
Read carefully command's man page!
For cp and mv, there is a -t switch, for target:
find . -type f -name '*.pdf' -exec cp -ait "/path to target" {} +
and
find . -type f -name '*.pdf' -exec mv -t "/path to target" {} +
Script way
There is an overall workaroung used in bash script:
#!/bin/bash
folder=( "/path to folder" "/path to anther folder" )
if [ "$1" != "--run" ] ;then
exec find "${folder[#]}" -type f -name '*.pdf' -exec $0 --run {} +
exit 0;
fi
shift
for file ;do
printf "Doing something with '%s'.\n" "$file"
done
What about a shorter and more reliable one?
for i in **/*.pdf; do rm "$i"; done
I had the same problem with a folder full of temporary images that was growing day by day and this command helped me to clear the folder
find . -name "*.png" -mtime +50 -exec rm {} \;
The difference with the other commands is the mtime parameter that will take only the files older than X days (in the example 50 days)
Using that multiple times, decreasing on every execution the day range, I was able to remove all the unnecessary files
You can create a temp folder, move all the files and sub-folders you want to keep into the temp folder then delete the old folder and rename the temp folder to the old folder try this example until you are confident to do it live:
mkdir testit
cd testit
mkdir big_folder tmp_folder
touch big_folder/file1.pdf
touch big_folder/file2.pdf
mv big_folder/file1,pdf tmp_folder/
rm -r big_folder
mv tmp_folder big_folder
the rm -r big_folder will remove all files in the big_folder no matter how many. You just have to be super careful you first have all the files/folders you want to keep, in this case it was file1.pdf
To delete all *.pdf in a directory /path/to/dir_with_pdf_files/
mkdir empty_dir # Create temp empty dir
rsync -avh --delete --include '*.pdf' empty_dir/ /path/to/dir_with_pdf_files/
To delete specific files via rsync using wildcard is probably the fastest solution in case you've millions of files. And it will take care of error you're getting.
(Optional Step): DRY RUN. To check what will be deleted without deleting. `
rsync -avhn --delete --include '*.pdf' empty_dir/ /path/to/dir_with_pdf_files/
.
.
.
Click rsync tips and tricks for more rsync hacks
I found that for extremely large lists of files (>1e6), these answers were too slow. Here is a solution using parallel processing in python. I know, I know, this isn't linux... but nothing else here worked.
(This saved me hours)
# delete files
import os as os
import glob
import multiprocessing as mp
directory = r'your/directory'
os.chdir(directory)
files_names = [i for i in glob.glob('*.{}'.format('pdf'))]
# report errors from pool
def callback_error(result):
print('error', result)
# delete file using system command
def delete_files(file_name):
os.system('rm -rf ' + file_name)
pool = mp.Pool(12)
# or use pool = mp.Pool(mp.cpu_count())
if __name__ == '__main__':
for file_name in files_names:
print(file_name)
pool.apply_async(delete_files,[file_name], error_callback=callback_error)
If you want to remove both files and directories, you can use something like:
echo /path/* | xargs rm -rf
I only know a way around this.
The idea is to export that list of pdf files you have into a file. Then split that file into several parts. Then remove pdf files listed in each part.
ls | grep .pdf > list.txt
wc -l list.txt
wc -l is to count how many line the list.txt contains. When you have the idea of how long it is, you can decide to split it in half, forth or something. Using split -l command
For example, split it in 600 lines each.
split -l 600 list.txt
this will create a few file named xaa,xab,xac and so on depends on how you split it.
Now to "import" each list in those file into command rm, use this:
rm $(<xaa)
rm $(<xab)
rm $(<xac)
Sorry for my bad english.
I ran into this problem a few times. Many of the solutions will run the rm command for each individual file that needs to be deleted. This is very inefficient:
find . -name "*.pdf" -print0 | xargs -0 rm -rf
I ended up writing a python script to delete the files based on the first 4 characters in the file-name:
import os
filedir = '/tmp/' #The directory you wish to run rm on
filelist = (os.listdir(filedir)) #gets listing of all files in the specified dir
newlist = [] #Makes a blank list named newlist
for i in filelist:
if str((i)[:4]) not in newlist: #This makes sure that the elements are unique for newlist
newlist.append((i)[:4]) #This takes only the first 4 charcters of the folder/filename and appends it to newlist
for i in newlist:
if 'tmp' in i: #If statment to look for tmp in the filename/dirname
print ('Running command rm -rf '+str(filedir)+str(i)+'* : File Count: '+str(len(os.listdir(filedir)))) #Prints the command to be run and a total file count
os.system('rm -rf '+str(filedir)+str(i)+'*') #Actual shell command
print ('DONE')
This worked very well for me. I was able to clear out over 2 million temp files in a folder in about 15 minutes. I commented the tar out of the little bit of code so anyone with minimal to no python knowledge can manipulate this code.
I have faced a similar problem when there were millions of useless log files created by an application which filled up all inodes. I resorted to "locate", got all the files "located"d into a text file and then removed them one by one. Took a while but did the job!
I solved with for
I am on macOS with zsh
I moved thousands only jpg files. Within mv in one line command.
Be sure there are no spaces or special characters in the name of the files you are trying to move
for i in $(find ~/old -type f -name "*.jpg"); do mv $i ~/new; done
A bit safer version than using xargs, also not recursive:
ls -p | grep -v '/$' | grep '\.pdf$' | while read file; do rm "$file"; done
Filtering our directories here is a bit unnecessary as 'rm' won't delete it anyway, and it can be removed for simplicity, but why run something that will definitely return error?
Using GNU parallel (sudo apt install parallel) is super easy
It runs the commands multithreaded where '{}' is the argument passed
E.g.
ls /tmp/myfiles* | parallel 'rm {}'
For remove first 100 files:
rm -rf 'ls | head -100'

Loop over file names from `find`?

If I run this command:
sudo find . -name *.mp3
then I can get a listing of lots of mp3 files.
Now I want to do something with each mp3 file in a loop. For example, I could create a while loop, and inside assign the first file name to the variable file. Then I could do something with that file. Next I could assign the second file name to the variable file and do with that, etc.
How can I realize this using a linux shell command? Any help is appreciated, thanks!
For this, use the read builtin:
sudo find . -name *.mp3 |
while read filename
do
echo "$filename" # ... or any other command using $filename
done
Provided that your filenames don't use the newline (\n) character, this should work fine.
My favourites are
find . -name '*.mp3' -exec cmd {} \;
or
find . -name '*.mp3' -print0 | xargs -0 cmd
While Loop
As others have pointed out, you can frequently use a while read loop to read filenames line by line, it has the drawback of not allowing line-ends in filenames (who uses that?).
xargs vs. -exec cmd {} +
Summarizing the comments saying that -exec...+ is better, I prefer xargs because it is more versatile:
works with other commands than just find
allows 'batching' (grouping) in command lines, say xargs -n 10 (ten at a time)
allows parallellizing, say xargs -P4 (max 4 concurrent processes running at a time)
does privilige separation (such as in the OP's case, where he uses sudo find: using -exec would run all commands as the root user, whereas with xargs that isn't necessary:
sudo find -name '*.mp3' -print0 | sudo xargs -0 require_root.sh
sudo find -name '*.mp3' -print0 | xargs -0 nonroot.sh
in general, pipes are just more versatile (logging, sorting, remoting, caching, checking, parallelizing etc, you can do that)
How about using the -exec option to find?
find . -name '*.mp3' -exec mpg123 '{}' \;
That will call the command mpg123 for every file found, i.e. it will play all the files, in the order they are found.
for file in $(sudo find . -name *.mp3);
do
# do something with file
done

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