标签： Linux

Description: xargs is used to pass arguments to other commands and is an essential component for building one-liner commands.

Syntax:
xargs [OPTIONS] [COMMAND]

Overview:
xargs takes input from stdin, separated by spaces or newline characters, and passes it as space-separated arguments to other commands. However, be careful when filenames or strings contain spaces, as xargs may misinterpret them.

Options:

• -0, --null: Default option. If stdin contains special characters like backticks (), backslashes (\), or spaces, xargs` restores them to regular characters.
• -a, --arg-file=FILE: Reads input from the specified file instead of stdin.
• -d, --delimiter=DEL: Specifies the delimiter to separate input. By default, xargs uses spaces and newlines, outputting arguments separated by spaces.
• -E EOF_STR: Sets an end-of-input string. If none is specified, input has no terminator. EOF_STR must be a separate field (i.e., space or newline separated).
• -e, --eof[=EOF_STR]: Same as -E, but non-POSIX compliant. Use -E if available.
• -I REPLACE_STR: Assigns each argument to the specified placeholder (e.g., {}, $, @). Useful for positioning arguments when there are multiple parameters. For example:find . -name "*.txt" | xargs -I {} cp {} /tmp/{}.bak

• -i, --replace[=REPLACE_STR]: Same as -I, but REPLACE_STR is optional and defaults to {}. Use -I for POSIX compliance.
• -L MAX_LINES: Limits the number of input lines per execution, implying the -x option.
• -l, --max-lines[=MAX_LINES]: Same as -L. Defaults to 1 line. Use -L for POSIX compliance.
• -n, --max-args=MAX_ARGS: Specifies the maximum number of arguments to pass to the command at once.
• -o, --open-tty: Reopens stdin to /dev/TTY before running the command in a subprocess, useful for interactive applications.
• -P, --max-procs=MAX_PROCS: Sets the maximum number of parallel processes. Default is 1. Use with -n or -L for batch processing.
• -p, --interactive: Prompts the user for confirmation before executing each command.
• --process-slot-var=NAME: Sets an environment variable with a unique value for each running subprocess. Once a process finishes, the value is reused.
• -r, --no-run-if-empty: Stops xargs from running if there is no input. This is the default behavior.
• -s, --max-chars=MAX_CHARS: Limits the maximum number of characters (including command, spaces, and newlines) in the command.
• --show-limits: Displays the system’s command-line length limitations.
• -t, --verbose: Prints the command to stderr before executing it.
• -x, --exit: Exits if the command line exceeds the specified character limit (-s).
• --help: Displays help information.
• --version: Displays version information.

Parameters:

• COMMAND: The command string to execute.

Examples:

Example 1
Some commands don’t accept piped arguments directly. Use xargs to pass them:

# Incorrect: `ls` cannot accept piped input directly
find /sbin -perm +700 | ls -l

# Correct: use `xargs` to pass arguments to `ls`
find /sbin -perm +700 | xargs ls -l

Example 2
Show system command-line length limitations:

$ xargs --show-limits

Example 3
Restore shell special characters like backticks:

$ echo '`0123`4 56789' | xargs -t echo

Example 4
Set the delimiter for reading input as a comma:

$ echo 01234 , 56789 | xargs -E ","

Example 5
Solve “argument list too long” errors when working with many files:

# Add a suffix to all files in the current directory
ls | xargs -t -i mv {} {}.bak

Example 6
Set how many lines to pass as arguments at a time:

$ echo -e "01234\n56789\n01234" | xargs -t -L 2 echo

Example 7
Merge multi-line input into a single line:

$ cat test.txt | xargs

Example 8
Kill processes in combination with ps, grep, awk, and kill:

$ ps -ef | grep spp | awk '{printf "%s ",$2}' | xargs kill -9