xargs

xargs is a command in Unix-like systems that reads items from standard input and executes a specified command using those items as arguments. It is commonly used to transform a stream of input into a batch of command invocations, especially when the number of items would exceed the argument length limit for a single command.

By default, xargs collects input items and runs the given program with as many arguments as possible. It continues processing input until none remains. This makes it useful with programs that produce lists, such as find, ls, or grep, to perform bulk operations on many files or strings.

Key options and behavior include:

- -n N limits the number of arguments per command invocation.

- -P N enables running up to N processes in parallel.

- -I replace-string allows inserting each input item at a specified location in the command.

- -d delim sets a custom input delimiter.

- -r prevents running the command if there is no input.

- -0 or --null makes xargs treat input items as null-terminated, which pairs with find -print0 to handle filenames containing spaces or newlines.

- -L N processes input after N lines per invocation.

- -t or -p can print or prompt before executing commands.

Common usage patterns include piping a list of files into a command, such as find . -type f -print0 | xargs -0 -I{} cp {} /backup, or processing items in fixed-size batches with -n. While xargs is robust for handling large input sets, using null-terminated input (-0) is recommended to safely handle spaces and special characters in filenames.