I have a large number of files on disk and trying to xargs with find to get faster output.
find . -printf '%m %p\n'|sort -nr
If I write find . -printf '%m %p\n'|xargs -0 -P 0 sort -nr, it gives error argument line is too long. Removing -0 option gives other error.
The parallelism commands such as xargs or GNU parallel
are applicable only if the task can be divided into multiple independent
jobs e.g. processing multiple files at once with the same command.
It is not possible to use sort command with these parallelism commands.
Although sort has --parallel option, it may not work well for
piped input. (Not fully evaluated.)
As side notes:
The mechanism of xargs is it reads items (filenames in most cases) from
the standard input and generates individual commands by combining
the argument list (command to be executed) with each item. Then you'll
see the syntax .. | xargs .. sort is incorrect because each filename
is passed to sort as an argument then sort tries to sort the contents
of the file.
The -0 option to xargs tells xargs that input items are delimited
by a null character instead of a newline. It is useful when the input
filenames contain special characters including a newline character.
In order to use this feature, you need to coherently handle the piped
stream in that way: putting -print0 option to find and -z option
to sort. Otherwise the items are wrongly concatenated and will cause
argument line is too long error.
Suggesting to use locate command instead of find command.
You might want to update files database with updatedb command.
Read more about locate command here.
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
Hundred times a day I need to search for patterns in files and sometime I have to replace these patterns with something else. Most of the time it is simple patterns like a word or a short sentence but sometime I have to look for more complex regexp. I don't really like sed (at least the sed version I have because it is not much compliant with the PCRE engine). So I rather prefer using perl -pi -e.
However, Perl pie is not very attractive on Cygwin because of the mandatory -i.bak temp files. I need to find a way to automatically remove the .bak files after processing. Moreover, if I want to replace recursively in a project I have to list all the files first:
find . | xargs -n1 perl -pi -e 's/foo/bar/'
This command is quite long to write especially if you use it thousand times a month. So I decided to write a more useful tool working in the same way as the great silver searcher ag.
ag 'foo\d{3}[^\w]' # Search for a pattern
# Oh yes this one should be renamed!
replace 's/(foo)\d{3}[^\w]/\U$1\E_bar/g'
I wrote this very primitive bash function
function replace
{
EXTENSION=.perlpie_tmp
perl -p -i$EXTENSION -e $1 ${*:2}
for file in ${*:2}; do
rm "$file$EXTENSION";
done;
}
But I am not satisfied at all because it doesn't automatically search for all files recursively if there is no more than one argument. I may either modify this function an add find . if the number of arguments is 1, or I can write a much complex program in Perl that can support command line options, pretty output, smart case search or even plain text search.
What is the most suitable option to this problem and is there any advanced search/replace tool on the linux world? If not I may try to write my own rip tool standing for replace-in-place which can support all the options that I need.
Before that I need some advices...
EDIT
Actually I think to fork https://github.com/petdance/ack2 to add a replacement feature... This may or may not be a good idea...
Here's an alternative to your function (edited to use the suggestion provided by gniourf_gniourf, thanks):
find -type f . -exec sh -c 'perl -pi.bak -e "s/foo/bar/" "$0" && rm -f "$0".bak' {} \;
Using this approach, you can remove the file as you go.
I think you can use
grep -Hrn -e "string" .
to find a pattern, and
find -type f -exec sed -i "s#string1#string2#g" {} \;
to replace a pattern
I would slightly modify your existing function:
function replace {
local perl_code=$1 EXTENSION=.perlpie_tmp file
shift
for file; do
perl -p -i$EXTENSION -e "$perl_code" "$file" && rm "$file$EXTENSION"
done;
}
This will slightly worsen the performance as you're now calling perl multiple times, but I suspect you won't notice.
Out of many results returned by grepping a particular pattern, if I want to use all the results one after the other in my script, how can I go about it?For e.g. I grep for .der in a certificate folder which returns many results. I want to use each and every .der certificate listed from the grep command. How can I use one file after the other out of the grep result?
Are you actually grepping content, or just filenames? If it's file names, you'd be better off using the find command:
find /path/to/folder -name "*.der" -exec some other commands {} ";"
It should be quicker in general.
One way is to use grep -l. This ensures you only get every file once. -l is used to print the name of each file only, not the matches.
Then, you can loop on the results:
for file in `grep ....`
do
# work on $file
done
Also note that if you have spaces in your filenames, there is a ton of possible issues. See Looping through files with spaces in the names on the Unix&Linux stackexchange.
You can use the output as part of a for loop, something like:
for cert in $(grep '\.der' *) ; do
echo ${cert} # or something else
done
Of course, if those der things are actually files (and you're using ls | grep to get them), you can directly use the files:
for cert in *.der ; do
echo ${cert} # or something else
done
In both cases, you may need to watch out for arguments with embedded spaces.
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?