130
votes
Accepted
How do I get xargs to show me the command lines it's generating without running them?
You may benefit from the -p or -t flags.
xargs -p or xargs --interactive will print out the command to be executed and then prompt for input (y/n) to confirm before executing the command.
% cat list
...
- 1,416
58
votes
How to quote arguments with xargs
I had a similar requirement and ended up using the -I switch to have a placeholder and I was able to quote it.
find . -size +1M | xargs -I {} echo "{}" # just for show (ha)
find . -size +1M ...
- 697
55
votes
Accepted
Passing multiple parameters via xargs
I believe that you can’t use -I that way.
But you can get the effect / behavior you want by saying:
echo {1..8} | xargs -n2 sh -c 'echo "the number $1 comes before $2"' sh
This, essentially, creates ...
- 10.9k
34
votes
Accepted
Why does 'top' fail to run via 'xargs'?
Turns out that there is a special option --open-tty in xargs for interactive applications like top. From man xargs:
-o, --open-tty
Reopen stdin as /dev/tty in the child process before
...
- 1,672
31
votes
Why does xargs strip quotes from input?
For GNU xargs, I found another solution in the manpage: explicitly specify delimiter to be '\n'. This turns off special handling for quotes:
--delimiter=delim, -d delim
Input items are terminated by ...
- 411
30
votes
Accepted
Copy multiple files using command `xargs`
As the cp error indicates, the target directory must come last. Since it looks like your cp doesn't have an equivalent of GNU cp's -t option, you have to get xargs to insert the filename between cp ...
- 77.9k
29
votes
find . -print0 | xargs -0 cmd vs find . -exec cmd {} +
TL;DR
There's no clear winner. My recommendation would be to use:
find . -exec cmd {} +
Wherever it's enough as it's more portable, uses less resource and has fewer issues, and one of:
xargs -r0 -...
- 584k
26
votes
How can I find files and then use xargs to move them?
Perhaps this command is possible now and wasn't back in 2013, but this works perfectly for me:
ls pattern* | xargs mv -t DESTINATION/
The -t key puts the destination folder first, freeing up mv ...
- 371
23
votes
Accepted
find and sed string in docker got error ` Device or resource busy`
Yes, as you found, the file is mounted by docker, which means you are not allowed to change its inode from within docker container. But, what if you only change the content of file without touching ...
- 1,361
23
votes
Accepted
How to give a comma-separated list as arguments to the next command
This should equally work as well:
s1 | xargs -d "," -n1 s2
Test case:
printf 1,2,3,4 | xargs -d ',' -n1 echo
Result:
1
2
3
4
If s1 outputs that list followed by a newline character, you'd want to ...
- 1,927
23
votes
Accepted
How can I get the index of the xargs "parallel processor"?
If you're using GNU xargs, there's --process-slot-var:
--process-slot-var=environment-variable-name
Set the environment variable environment-variable-name to a unique
value in each running child ...
- 77.9k
21
votes
Why does 'top' fail to run via 'xargs'?
top is an interactive program, for instance you can type i to toggle showing idle processes. Whilst it could arrange to read from /dev/tty in practice it expects that stdin is connected to the ...
- 19.1k
20
votes
Accepted
If no input is given to xargs, don't let xargs run the utility
You are looking for the -r option. This is a non-standard option which may be implemented on your system (check your xargs manual).
From the GNU xargs manual:
-r, --no-run-if-empty
If the standard ...
- 356k
17
votes
Accepted
How do I create directories named after each month?
With -I, xargs gets one argument per line as opposed to the default of one argument per (blank or newline delimited, possibly quoted) word without -I (and implies -n). So in your example date is ...
- 584k
17
votes
Accepted
How to get the total duration of all video files in current folder and sub-directories
With exiftool:
$ exiftool -ext mp4 -r -n -q -p '${Duration;$_ = ConvertDuration(our $total += $_)}' . | tail -n 1
4 days 22:14:59
The main difference from @don_cristi's answer to a very similar ...
- 584k
16
votes
Piping commands after a piped xargs
Just in addition to fredtantini and as a general clarification (since the docs are a bit confusing):
The xargs -I {} will take the '{}' characters from the standard input and replace them with ...
- 271
16
votes
Accepted
Why xargs does not process the last argument?
What went wrong
b appears in the output, so it was processed, just not the way you expected.
As a first step, ask bash to tell you what it sees: pass the -x option to enable its traces.
$ echo a b | ...
14
votes
passing a '-9' to xargs kill command
Example how to close php processes in batch. php you can replace using whatever your process has name:
ps -aux | grep php | awk '{print $2}' | xargs kill -9
14
votes
Accepted
find -exec {} + argument list limit
Yes, find -exec ... {} + runs the given command as many times as necessary to accommodate all the arguments without exceeding the maximum argument list size in each invocation. This is specified by ...
- 481k
14
votes
Accepted
Move all files NOT ending with .txt
The simple shell loop variant (in bash):
shopt -s extglob dotglob nullglob
for pathname in ~username/data/!(*.txt); do
! test -d "$pathname" && mv "$pathname" ~username/data/other_files
...
- 356k
14
votes
Accepted
Why do I get an error when deleting entries from Bash history?
The error is raised because xargs cannot find a history command. It is a shell builtin, as you can confirm with type history, thus not visible to xargs. Try
echo 1 | xargs history -d; echo $?
The ...
- 19.4k
13
votes
Accepted
Xargs to extract filename
Just do:
for f in *.html; do printf '%s\n' "[${f%.*}](./$f)"; done > index.md
Use set -o nullglob (zsh, yash) or shopt -s nullglob (bash) for *.html to expand to nothing instead of *.html (or ...
- 584k
13
votes
How does xargs know when a stdin input ends, so that it can start processing it?
To read its input, xargs uses the read function (see also the corresponding Linux manpage).
read reads the next available data from a file descriptor into an area of memory specified by the calling ...
- 481k
13
votes
Accepted
Reliable way to open files given by the result of find … -exec grep … {} \+
vim $(find path/ -exec grep -l 'pattern' {} +)
is an unquoted command substitution, so word splitting will be performed on whitespace on its result, as well as pathname expansion. I.e., if a file a b ...
- 19.4k
12
votes
How to repeat variables twice in xargs
Another option is to use -i flag, which is the same as -I{} (it implies that the replacement is given with {}):
$ echo test | xargs -i echo {} {}
- 573
12
votes
echo list / array to xargs
printf '%s\n' "${list[@]}" | xargs
This would print each element of list on its own line and that newline-delimited list would be passed to xargs.
"${list[@]}" would expand to the ...
- 356k
12
votes
Accepted
Use xargs and kill in script with optional signal
The problem is that you’re explicitly adding a space to SIGNAL:
SIGNAL=" -${SIGNAL}"
and then referencing it in quotes:kill "$SIGNAL"
Since kill is seeing an argument that doesn’t ...
12
votes
Accepted
Run command on each line of CSV file, using fields in different places of the command
GNU parallel can read csv directly, and has item replacement built in.
More or less directly taken from man parallel:
parallel --csv 'my_cmd --arg1 {2} --arg2 {1} --arg3 {3}' :::: file.csv
Add -j1 ...
- 51.2k
11
votes
Piping commands after a piped xargs
GNU Parallel makes this kind of tasks easy:
find . -type d -name "*log*" | parallel --tag "ls -la {} | tail -2"
If you do not want to do a full install of GNU Parallel you can do a minimal ...
- 37.5k
11
votes
Accepted
xargs with rm + filename containing spaces
xargs -d "\n" -I {} rm \"{}\"
This assumes GNU coreutils' version of xargs that supports the -d option for specifying the delimiter.
This will not work together with your find command because it adds ...
- 356k
Only top scored, non community-wiki answers of a minimum length are eligible