xargs Command: Usage, the -n and -I Options and Using It with find

The xargs command is a Linux tool that turns lines and words received on standard input into arguments for another command and runs it. When we passed three log files found by find to wc through xargs in a working folder on an AlmaLinux 9 server, one file with a space in its name was split in two and caused an error, and with -print0 and -0 the line counts of all three files appeared.

The output below was run inside a working folder under the root account on an AlmaLinux 9.8 server. The name list, logs and temporary files are sample files made for testing, and the IP addresses and working folder paths in them are also example values.

1️⃣ Basic xargs command usage

xargs splits the standard input passed by the previous command on spaces and newlines, and runs the command written after it with those pieces in its argument positions. We checked this with names.txt, which holds one name per line.

cat names.txt

alice
bob
carol
dave
erin

Passing the output of cat to xargs echo turns the five lines into arguments of a single echo, printed on one line.

cat names.txt | xargs echo

alice bob carol dave erin

If you write no command after it, xargs runs echo, so the result is the same.

cat names.txt | xargs

alice bob carol dave erin

A pipe connects the output of the previous command to the standard input of the next one, so nothing goes into the next command's argument positions. If you only pipe list.txt, which holds three file names, to wc -l, wc counts the 3 lines of the list itself.

cat list.txt

logs/access.log
logs/error.log
tmp/keep.txt

cat list.txt | wc -l

3

With xargs in between, the three names in the list become arguments of wc, and the line count appears for each file.

cat list.txt | xargs wc -l

  3 logs/access.log
  2 logs/error.log
  1 tmp/keep.txt
  6 total

2️⃣ The xargs -n and -I options

Without options, all input goes into one run of the command, so to repeat the command, use -n to set how many arguments are passed at a time. The figure below shows how the same five names are grouped depending on the option.

-n 1 runs echo for each name, printing five lines.

cat names.txt | xargs -n 1 echo

alice
bob
carol
dave
erin

-n 2 groups them in twos and passes the one left over on its own.

cat names.txt | xargs -n 2 echo

alice bob
carol dave
erin

To see the commands being run, add -t. The command line appears first, with its output below it.

cat names.txt | xargs -t -n 2 echo

echo alice bob
alice bob
echo carol dave
carol dave
echo erin
erin

If an argument must go somewhere other than the end of the command, set a placeholder with -I. One line goes in place of {} at a time, and if the same text appears several times, all of them are replaced.

cat names.txt | xargs -I {} echo 'user: {}'

user: alice
user: bob
user: carol
user: dave
user: erin

cat names.txt | xargs -I {} echo '{} -> home/{}'

alice -> home/alice
bob -> home/bob
carol -> home/carol
dave -> home/dave
erin -> home/erin

You can make a folder per name in the same way. Create the home folder first, then use -I {} to make a folder per name under it, and five folders appear.

mkdir home

cat names.txt | xargs -I {} mkdir home/{}

ls home

alice  bob  carol  dave  erin

-I treats one line as one argument, so it cannot be used with -n. When we wrote both, -I was ignored with a warning and {} was printed as literal text.

cat names.txt | xargs -I {} -n 2 echo {}

xargs: warning: options --replace and --max-args/-n are mutually exclusive, ignoring previous --replace value
{} alice bob
{} carol dave
{} erin

-L groups by line count. If a line holds several words, the words on that line are passed together, and in names.txt, with one name per line, -L 2 gave the same result as -n 2.

cat names.txt | xargs -L 2 echo

alice bob
carol dave
erin

3️⃣ Combining find and xargs

You do not have to build a name list by hand; you can pass the files found by find straight to xargs. Looking for files ending in .log in the log folder finds three, and one of them has a space in its name.

find /root/work/logs -name '*.log'

/root/work/logs/access.log
/root/work/logs/error.log
/root/work/logs/old access.log

When this list went straight to xargs wc -l, the name with a space split into old and access.log, giving two error lines, and the total was 5 lines from only two files.

find /root/work/logs -name '*.log' | xargs wc -l

  3 /root/work/logs/access.log
  2 /root/work/logs/error.log
wc: /root/work/logs/old: No such file or directory
wc: access.log: No such file or directory
  5 total

find's -print0 separates names with the null character instead of a newline, and xargs's -0 splits arguments only on that null character. Using both gives the line counts of all three files, including the one with a space.

find /root/work/logs -name '*.log' -print0 | xargs -0 wc -l

  3 /root/work/logs/access.log
  2 /root/work/logs/error.log
  1 /root/work/logs/old access.log
  6 total

find's -exec option does the same job. With + after {}, the found files are passed at once, so the result is the same, and find passes spaces in file names as they are. xargs also accepts output from commands other than find, so use it when input does not come from find alone, or when you need to set how many items are passed at a time (-n) or how many run at once (-P).

find /root/work/logs -name '*.log' -exec wc -l {} +

  3 /root/work/logs/access.log
  2 /root/work/logs/error.log
  1 /root/work/logs/old access.log
  6 total

To pick only the found files containing a string, add grep -l after xargs. Two files contained wp-login: the access log and the error log.

find /root/work/logs -name '*.log' -print0 | xargs -0 grep -l wp-login

/root/work/logs/access.log
/root/work/logs/error.log

4️⃣ Deleting files with the xargs command

With rm after xargs, the found files are deleted at once, so check which files will be passed before deleting. Putting echo in front of rm prints only the command line that would run, and the files stay in place.

find /root/work/tmp -name '*.tmp' -print0 | xargs -0 echo rm

rm /root/work/tmp/cache-a.tmp /root/work/tmp/cache-b.tmp /root/work/tmp/cache-c.tmp

ls tmp

cache-a.tmp  cache-b.tmp  cache-c.tmp  keep.txt

With -p, xargs asks whether to run each command. Entering n deletes nothing, so the three temporary files stay.

find /root/work/tmp -name '*.tmp' -print0 | xargs -0 -p rm

rm /root/work/tmp/cache-a.tmp /root/work/tmp/cache-b.tmp /root/work/tmp/cache-c.tmp?...n

ls tmp

cache-a.tmp  cache-b.tmp  cache-c.tmp  keep.txt

Entering y deletes the three files, leaving only keep.txt.

find /root/work/tmp -name '*.tmp' -print0 | xargs -0 -p rm

rm /root/work/tmp/cache-a.tmp /root/work/tmp/cache-b.tmp /root/work/tmp/cache-c.tmp?...y

ls tmp

keep.txt

If input is empty, xargs runs the command once with no arguments. Passing an empty file runs rm with no arguments and gives the [rm: missing operand] error; with -r, the command does not run at all.

cat empty.txt | xargs rm

rm: missing operand
Try 'rm --help' for more information.

cat empty.txt | xargs -r rm

5️⃣ xargs parallel execution, delimiters and options

🔲 Parallel execution and delimiters

When commands run one at a time, the time grows with the number of targets. -P sets how many commands run at once. Four sleeps waiting 1, 2, 3 and 4 seconds took 10 seconds one after another, and finished in 4 seconds, the longest one, when run together with -P 4.

time seq 1 4 | xargs -n 1 sleep

real	0m10.007s
user	0m0.004s
sys	0m0.003s

time seq 1 4 | xargs -n 1 -P 4 sleep

real	0m4.005s
user	0m0.001s
sys	0m0.006s

If input is split by a symbol rather than newlines or spaces, set the delimiter with -d. Splitting three comma-joined names with -d , prints one line per name.

printf 'alice,bob,carol' | xargs -d , -n 1 echo

alice
bob
carol

To read from a file instead of standard input, give the file name to -a. The five names in names.txt went to echo without a pipe.

xargs -a names.txt echo

alice bob carol dave erin

🔲 xargs command options

📌 Main options: results from this article

📎 Other options: per the official manual

🔲 xargs command simulator

In the simulator below, you can type xargs and find commands yourself on the same test files.

🔢 FAQ & Recommended Content

🔗 Recommended Reading

Search · finding files Linux find command The find command finds files by name, type and time. It is the command most often placed before xargs, so read it next to widen your search conditions. Read post →

String search Linux grep command The grep command finds lines matching strings and regular expressions inside files. Use it to search several files passed through xargs at once. Deleting files Linux rm command An article on the rm command, which deletes files and folders, and the dangers of the -rf option. Check the options before putting rm after xargs. Ending processes Linux kill command The kill command sends a signal to a process ID to end it. Use it next when you pass a list of process IDs through xargs to end them.

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