I'm trying to copy a bunch of files below a directory and a number of the files have spaces and single-quotes in their names. When I try to string together find and grep with xargs, I get the following error:
find .|grep "FooBar"|xargs -I{} cp "{}" ~/foo/bar
xargs: unterminated quote
Any suggestions for a more robust usage of xargs?
This is on Mac OS X 10.5.3 (Leopard) with BSD xargs.
You can combine all of that into a single find command:
find . -iname "*foobar*" -exec cp -- "{}" ~/foo/bar \;
This will handle filenames and directories with spaces in them. You can use -name to get case-sensitive results.
Note: The -- flag passed to cp prevents it from processing files starting with - as options.
find . -print0 | grep --null 'FooBar' | xargs -0 ...
I don't know about whether grep supports --null, nor whether xargs supports -0, on Leopard, but on GNU it's all good.
The easiest way to do what the original poster wants is to change the delimiter from any whitespace to just the end-of-line character like this:
find whatever ... | xargs -d "\n" cp -t /var/tmp
This is more efficient as it does not run "cp" multiple times:
find -name '*FooBar*' -print0 | xargs -0 cp -t ~/foo/bar
I ran into the same problem. Here's how I solved it:
find . -name '*FoooBar*' | sed 's/.*/"&"/' | xargs cp ~/foo/bar
I used sed to substitute each line of input with the same line, but surrounded by double quotes. From the sed man page, "...An ampersand (``&'') appearing in the replacement is replaced by the string matching the RE..." -- in this case, .*, the entire line.
This solves the xargs: unterminated quote error.
This method works on Mac OS X v10.7.5 (Lion):
find . | grep FooBar | xargs -I{} cp {} ~/foo/bar
I also tested the exact syntax you posted. That also worked fine on 10.7.5.
Just don't use xargs. It is a neat program but it doesn't go well with find when faced with non trivial cases.
Here is a portable (POSIX) solution, i.e. one that doesn't require find, xargs or cp GNU specific extensions:
find . -name "*FooBar*" -exec sh -c 'cp -- "$#" ~/foo/bar' sh {} +
Note the ending + instead of the more usual ;.
This solution:
correctly handles files and directories with embedded spaces, newlines or whatever exotic characters.
works on any Unix and Linux system, even those not providing the GNU toolkit.
doesn't use xargs which is a nice and useful program, but requires too much tweaking and non standard features to properly handle find output.
is also more efficient (read faster) than the accepted and most if not all of the other answers.
Note also that despite what is stated in some other replies or comments quoting {} is useless (unless you are using the exotic fishshell).
Look into using the --null commandline option for xargs with the -print0 option in find.
For those who relies on commands, other than find, eg ls:
find . | grep "FooBar" | tr \\n \\0 | xargs -0 -I{} cp "{}" ~/foo/bar
find | perl -lne 'print quotemeta' | xargs ls -d
I believe that this will work reliably for any character except line-feed (and I suspect that if you've got line-feeds in your filenames, then you've got worse problems than this). It doesn't require GNU findutils, just Perl, so it should work pretty-much anywhere.
I have found that the following syntax works well for me.
find /usr/pcapps/ -mount -type f -size +1000000c | perl -lpe ' s{ }{\\ }g ' | xargs ls -l | sort +4nr | head -200
In this example, I am looking for the largest 200 files over 1,000,000 bytes in the filesystem mounted at "/usr/pcapps".
The Perl line-liner between "find" and "xargs" escapes/quotes each blank so "xargs" passes any filename with embedded blanks to "ls" as a single argument.
Frame challenge — you're asking how to use xargs. The answer is: you don't use xargs, because you don't need it.
The comment by user80168 describes a way to do this directly with cp, without calling cp for every file:
find . -name '*FooBar*' -exec cp -t /tmp -- {} +
This works because:
the cp -t flag allows to give the target directory near the beginning of cp, rather than near the end. From man cp:
-t, --target-directory=DIRECTORY
copy all SOURCE arguments into DIRECTORY
The -- flag tells cp to interpret everything after as a filename, not a flag, so files starting with - or -- do not confuse cp; you still need this because the -/-- characters are interpreted by cp, whereas any other special characters are interpreted by the shell.
The find -exec command {} + variant essentially does the same as xargs. From man find:
-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 invoca‐
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 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 immedi‐
ate exit, so some pending commands may not be run at all. This
variant of -exec always returns true.
By using this in find directly, this avoids the need of a pipe or a shell invocation, such that you don't need to worry about any nasty characters in filenames.
With Bash (not POSIX) you can use process substitution to get the current line inside a variable. This enables you to use quotes to escape special characters:
while read line ; do cp "$line" ~/bar ; done < <(find . | grep foo)
Be aware that most of the options discussed in other answers are not standard on platforms that do not use the GNU utilities (Solaris, AIX, HP-UX, for instance). See the POSIX specification for 'standard' xargs behaviour.
I also find the behaviour of xargs whereby it runs the command at least once, even with no input, to be a nuisance.
I wrote my own private version of xargs (xargl) to deal with the problems of spaces in names (only newlines separate - though the 'find ... -print0' and 'xargs -0' combination is pretty neat given that file names cannot contain ASCII NUL '\0' characters. My xargl isn't as complete as it would need to be to be worth publishing - especially since GNU has facilities that are at least as good.
For me, I was trying to do something a little different. I wanted to copy my .txt files into my tmp folder. The .txt filenames contain spaces and apostrophe characters. This worked on my Mac.
$ find . -type f -name '*.txt' | sed 's/'"'"'/\'"'"'/g' | sed 's/.*/"&"/' | xargs -I{} cp -v {} ./tmp/
If find and xarg versions on your system doesn't support -print0 and -0 switches (for example AIX find and xargs) you can use this terribly looking code:
find . -name "*foo*" | sed -e "s/'/\\\'/g" -e 's/"/\\"/g' -e 's/ /\\ /g' | xargs cp /your/dest
Here sed will take care of escaping the spaces and quotes for xargs.
Tested on AIX 5.3
I created a small portable wrapper script called "xargsL" around "xargs" which addresses most of the problems.
Contrary to xargs, xargsL accepts one pathname per line. The pathnames may contain any character except (obviously) newline or NUL bytes.
No quoting is allowed or supported in the file list - your file names may contain all sorts of whitespace, backslashes, backticks, shell wildcard characters and the like - xargsL will process them as literal characters, no harm done.
As an added bonus feature, xargsL will not run the command once if there is no input!
Note the difference:
$ true | xargs echo no data
no data
$ true | xargsL echo no data # No output
Any arguments given to xargsL will be passed through to xargs.
Here is the "xargsL" POSIX shell script:
#! /bin/sh
# Line-based version of "xargs" (one pathname per line which may contain any
# amount of whitespace except for newlines) with the added bonus feature that
# it will not execute the command if the input file is empty.
#
# Version 2018.76.3
#
# Copyright (c) 2018 Guenther Brunthaler. All rights reserved.
#
# This script is free software.
# Distribution is permitted under the terms of the GPLv3.
set -e
trap 'test $? = 0 || echo "$0 failed!" >& 2' 0
if IFS= read -r first
then
{
printf '%s\n' "$first"
cat
} | sed 's/./\\&/g' | xargs ${1+"$#"}
fi
Put the script into some directory in your $PATH and don't forget to
$ chmod +x xargsL
the script there to make it executable.
bill_starr's Perl version won't work well for embedded newlines (only copes with spaces). For those on e.g. Solaris where you don't have the GNU tools, a more complete version might be (using sed)...
find -type f | sed 's/./\\&/g' | xargs grep string_to_find
adjust the find and grep arguments or other commands as you require, but the sed will fix your embedded newlines/spaces/tabs.
I used Bill Star's answer slightly modified on Solaris:
find . -mtime +2 | perl -pe 's{^}{\"};s{$}{\"}' > ~/output.file
This will put quotes around each line. I didn't use the '-l' option although it probably would help.
The file list I was going though might have '-', but not newlines. I haven't used the output file with any other commands as I want to review what was found before I just start massively deleting them via xargs.
I played with this a little, started contemplating modifying xargs, and realised that for the kind of use case we're talking about here, a simple reimplementation in Python is a better idea.
For one thing, having ~80 lines of code for the whole thing means it is easy to figure out what is going on, and if different behaviour is required, you can just hack it into a new script in less time than it takes to get a reply on somewhere like Stack Overflow.
See https://github.com/johnallsup/jda-misc-scripts/blob/master/yargs and https://github.com/johnallsup/jda-misc-scripts/blob/master/zargs.py.
With yargs as written (and Python 3 installed) you can type:
find .|grep "FooBar"|yargs -l 203 cp --after ~/foo/bar
to do the copying 203 files at a time. (Here 203 is just a placeholder, of course, and using a strange number like 203 makes it clear that this number has no other significance.)
If you really want something faster and without the need for Python, take zargs and yargs as prototypes and rewrite in C++ or C.
You might need to grep Foobar directory like:
find . -name "file.ext"| grep "FooBar" | xargs -i cp -p "{}" .
If you are using Bash, you can convert stdout to an array of lines by mapfile:
find . | grep "FooBar" | (mapfile -t; cp "${MAPFILE[#]}" ~/foobar)
The benefits are:
It's built-in, so it's faster.
Execute the command with all file names in one time, so it's faster.
You can append other arguments to the file names. For cp, you can also:
find . -name '*FooBar*' -exec cp -t ~/foobar -- {} +
however, some commands don't have such feature.
The disadvantages:
Maybe not scale well if there are too many file names. (The limit? I don't know, but I had tested with 10 MB list file which includes 10000+ file names with no problem, under Debian)
Well... who knows if Bash is available on OS X?
Related
I'm attempting to find all .PHP files that are in certain depth of a directory (at least 4 levels down, but not more than 5 levels in).
I'm logged into my Centos server with root authority via shell.
The string I want to search for is:
$slides='';
What I have in front of me.. I would expect it to work. I tried to escape the $ with a \ (I thought perhaps it works like regex, needing special chars excluded). I tried without the ='' portion, or tried adding \'\' to that part.. or remove the ='' altogether to simplify. nothing.
find . -maxdepth 5 -mindepth 4 -type f -name ‘*.php’ -print | xargs grep "\$slides=’’" *
I'm already running it under the directory under which I want to recursively search.
Also - I have the filter to look for *.php only but I still get a bunch of directory names in the return with a warning that says grep: [dir_name]: Is a directory
Clearly I am missing something here as far as syntax of grep command goes, or how the filter works here. I use grep more in PHP so this is quite a transition for me!
So you were almost right. The problem looks to have been the grep part of the command
grep "\$slides=''" *
Namely the * was the issue. From the bash manual
After word splitting, unless the -f option has been set (see The Set
Builtin), Bash scans each word for the characters ‘*’, ‘?’, and ‘[’.
If one of these characters appears, and is not quoted, then the word
is regarded as a pattern, and replaced with an alphabetically sorted
list of filenames matching the pattern
When you piped the found files with find into xargs and attempted to grep them with *, grep would have interpreted this as you wanting to find the string $slides='' in a list of filenames/directories returned by the glob *, and you cannot grep directories without supplying the -r flag to grep, so it returned an error.
Instead, what you wanted to do is pipe the found files with find into xargs so it can add the list of filenames to the grep command, as that's what xargs does. From the xargs manual
xargs reads items from the standard input, delimited by blanks (which
can be protected with double or single quotes or a backslash) or
newlines, and executes the command (default is /bin/echo) one or more
times with any initial- arguments followed by items read from
standard input. Blank lines on the standard input are ignored.
Making the correct command
find . -maxdepth 5 -mindepth 4 -type f -name '*.php' -print0 | xargs -0 grep "\$slides=''"
Using the -print0 flag in find, and the -0 flag in xargs, to use NUL as the delimiter, in case any filenames contained newlines.
If you want to use shell_exec from your PHP code, it is a program execution function which allows you to run a command like 'ls -al' in the operating system shell and get the result returned into a variable. Querystrings are not commands you can use in this way.
Do you mean running PHP from the command line so that it runs from the shell, not from the web server:
php -r 'echo "hello world\n";'
If you run PHP 4.3 and above, you can use the PHP Command Line Interface (CLI) which can also execute scripts stored in files. Have a look at the syntax and examples at: http://php.net/features.commandline
I am needing pipe this result:
grep -R "extends Some_Critical_Class" *
to another grep:
grep "function init("
ie. "files that extend Some_Critical_Class that also have function init()"
If there is a way to do it in one operation in grep, that would be great, but I'd also like to see the how the piping is done to improve my programming in *nix (which is rudimentary right now). Thanks.
To be clear, you want the list of files that contain both strings. Not only you need two greps for this, but you also need the -l (a.k.a. --files-with-matches) option.
Here is one way of doing this:
grep -F -R -l -Z "extends Some_Critical_Class" . \
| xargs -0 grep -F -l "function init("
We first obtain a (NUL-delimited) list of files that contain your first string, and then we use xargs to pass this list of files to the second grep.
Don't use grep (g/re/p) to find files, adding that functionality to GNU grep was just a bad idea since there's already a perfectly good tool to find files with an extremely obvious name.
You didn't say what your expected output was but maybe this does what you want:
find . -type f -exec \
awk '
/extends Some_Critical_Class/ { x=1 }
/function init\(/ { y=1 }
END { if (x && y) print FILENAME }
' {} \;
The above will work on any Unix box, not just one with GNU tools, and can be trivially modified to add more regexps or strings to search for, various "and" and "or" combinations, etc.
I'm trying to use the sed command in terminal to replace a specific line in all my text files with a certain extension by a specific string:
sed -i.bak '35s/^.*$/5\) 1\-4/' fitting_file*.feedme
So I am trying to replace line 35 in each of these files with the string "5) 1-4". When I run an ls fitting_file*.feedme | wc -l command in this directory, I get 221 files. However, when I run the above sed command, it only edits the FIRST file in the order of ls fitting_file*.feedme. I know this because grep '5) 1-4' fitting_file*.feedme continually only returns the first file on the list after I run the replacement command. I also tried replacing fitting_file*.feedme with a space-separated list of a couple of these files in my sed command as a test, but it still only operated on the one I chose to list first. Why is this happening?
sed operates on a single stream. It essentially concats all the files together and treats that as a single stream. So it replaces the 35th line of the big concatenated stream.
To see this, make a 20 line file called A and a 20 line file called B. Apply your sed command as
sed -i.bak '35s/^.*$/5\) 1\-4/' A B
and you will see the 15th line of B replaced.
I think this should answer your direct question. As far how to get done what you like, I assume you've already figured out that wrapping your sed command in a for is one way to do it. :)
Try
Create a file containing your sed instruction like this
#!/bin/bash
sed -i.bak '35s/^.*$/5\) 1\-4/' $1
exit 0
and call it prog.sh. Next make it executable :
chmod u+x prog.sh
now you can solve your problem using
find . -name fitting_file\*.feedme -exec ./prog.sh {} \;
You could do all this on one line but frankly the number of escapes required is a bit much. Good luck.
To do what you're trying to do without using a shell loop is:
awk -i inplace -v inplace::suffix=.bak 'FNR==35{$0="5) 1-4"}1' fitting_file*.feedme
Note that unlike sed which can just count lines across all input files, awk has NR to track the number of records (lines by default) across all files and FNR for the same but just within the current file.
The above uses GNU awk for inplace editing just like GNU sed has -i for that. The default awk on MacOS is BSD awk, not GNU awk, but you should install GNU awk as it doesn't have all the bugs/quirks that BSD awk does and it has a ton of extremely useful extensions.
If you just want to use MacOS's awk then it'd be something like:
find . -name 'fitting_file*.feedme' -exec sh -c "\
awk 'FNR==35{\$0=\"5) 1-4\"}1' \"\$1\" > \"\$1.bak\" &&
mv -- \"\$1.bak\" \"\$1\"
" sh {} \;
which is obviously getting kinda complicated - I'd probably put the awk+mv script in a file to execute from sh -c or just resort to a shell loop myself if faced with that alternative (or a similar quoting nightmare with xargs)!
This might be a very simple thing for a shell scripting programmer but am pretty new to it. I was trying to execute the below command in a shell script and save the output into a variable
inputfile=$(ls -ltr *.{PDF,pdf} | head -1 | awk '{print $9}')
The command works fine when I fire it from terminal but fails when executed through a shell script (sh). Why is that the command fails, does it mean that shell script doesn't support the command or am I doing it wrong? Also how do I know if a command will work in shell or not?
Just to give you a glimpse of my requirement, I was trying to get the oldest file from a particular directory (I also want to make sure upper case and lower case extensions are handled). Is there any other way to do this ?
The above command will work correctly only if BOTH *.pdf and *.PDF files are in the directory you are currently.
If you would like to execute it in a directory with only one of those you should consider using e.g.:
inputfiles=$(find . -maxdepth 1 -type f \( -name "*.pdf" -or -name "*.PDF" \) | xargs ls -1tr | head -1 )
NOTE: The above command doesn't work with files with new lines, or with long list of found files.
Parsing ls is always a bad idea. You need another strategy.
How about you make a function that gives you the oldest file among the ones given as argument? the following works in Bash (adapt to your needs):
get_oldest_file() {
# get oldest file among files given as parameters
# return is in variable get_oldest_file_ret
local oldest f
for f do
[[ -e $f ]] && [[ ! $oldest || $f -ot $oldest ]] && oldest=$f
done
get_oldest_file_ret=$oldest
}
Then just call as:
get_oldest_file *.{PDF,pdf}
echo "oldest file is: $get_oldest_file_ret"
Now, you probably don't want to use brace expansions like this at all. In fact, you very likely want to use the shell options nocaseglob and nullglob:
shopt -s nocaseglob nullglob
get_oldest_file *.pdf
echo "oldest file is: $get_oldest_file_ret"
If you're using a POSIX shell, it's going to be a bit trickier to have the equivalent of nullglob and nocaseglob.
Is perl an option? It's ubiquitous on Unix.
I would suggest:
perl -e 'print ((sort { -M $b <=> -M $a } glob ( "*.{pdf,PDF}" ))[0]);';
Which:
uses glob to fetch all files matching the pattern.
sort, using -M which is relative modification time. (in days).
fetches the first element ([0]) off the sort.
Prints that.
As #gniourf_gniourf says, parsing ls is a bad idea. Such as leaving unquoted globs, and generally not counting for funny characters in file names.
find is your friend:
#!/bin/sh
get_oldest_pdf() {
#
# echo path of oldest *.pdf (case-insensitive) file in current directory
#
find . -maxdepth 1 -mindepth 1 -iname "*.pdf" -printf '%T# %p\n' \
| sort -n \
| tail -1 \
| cut -d\ -f1-
}
whatever=$(get_oldest_pdf)
Notes:
find has numerous ways of formatting the output, including
things like access time and/or write time. I used '%T# %p\n',
where %T# is last write time in UNIX time format incl.fractal part.
This will never containt space so it's safe to use as separator.
Numeric sort and tail get the last item, sorting by the time,
cut removes the time from the output.
I used IMO much easier to read/maintain pipe notation, with help of \.
the code should run on any POSIX shell,
You could easily adjust the function to parametrize the pattern,
time used (access/write), control the search depth or starting dir.
Can someone please give me an example of using xargs on the below operation?
tar c $dir/temp/*.parse\
| lzma -9 > $dir/backup/$(date '+%Y-%m-%d')-archive.tar.lzma
I get the error from bash "/bin/tar: Argument list too long"
Particularily I am trying to do LZMA compression on about 4,500 files; so this isn't surprising. I just don't know how to modify the above to use xargs and get rid of the error! Thanks.
Expanding on CristopheDs answer and assuming you're using bash:
tar c --files-from <(find $dir/temp -maxdepth 1 -name "*.parse") | lzma -9 > $dir/backup/$(date '+%Y-%m-%d')-archive.tar.lzma
The reason xargs doesn't help you here is that it will do multiple invocations until all arguments have been used. This won't help you here since that will create several tar archives, which you don't want.
As a side note:
Always, always avoid xargs(1). It's a broken tool and is only remotely useful if you use it with the -0 option. Even then, it's almost always better to use find(1)'s -exec option, or a simple for or while loop.
Why is xargs so bad? Firstly, it splits input on whitespace, meaning all your filenames that contain whitespace will cause havoc. Secondly, it tries to be a smartass, and parse quotes for you. Which only leads to more headaches as you use it on filenames that contain quotes as part of the filename, such as songs: "I don't wanna miss a thing.mp3". This will just make xargs puke and curse at you that you quoted its input badly. No, you didn't: it should just learn that quotes do not belong in input data, they belong in shell scripts, and xargs has no business trying to parse them.
Mind you, xargs(1) doesn't do the whitespace splitting or the quote parsing when you pass -0 to it. It does the right thing, which is use NULL bytes to delimit filenames. But that means you need to give it input that uses NULL byte-delimited filenames (such as "find -foo -print0"). Which brings us back to: it's better to just use find's -exec: "find -foo -exec bar {} +".
Use find to pipe the 'wanted' filenames to a temporary file,
and then use tar with the '-–files-from' command line option.
Edit:
or pipe them directly into each other to avoid the temporary file.
So: use find to list the wanted filenames | tar ... --files-from
Perhaps you want something like this?
find $dir/temp/ -name '*.parse' -print0 | tar --null -T - -c | lzma -9 > $dir/backup/$(date '+%Y-%m-%d')-archive.tar.lzma
Since you're on Linux, you have GNU tar, and you can use the '-F -' or '--files-from' option to read the file names.
However, you can also use:
--use-compress-program="lzma -9"
to specify the compression program to use, and simply give the compresses file name as the target file for the 'tar' command.
This was necessary for 'bzip2' compression before the '-j' option was added.