Terminate if a command line containing number arguments (see the -n option above) [XSI] or number lines (see the -L option above) [/XSI] will not fit in the implied or specified size (see the -s option above).

Terminate if a constructed command line will not fit in the implied or specified size (see the -s option above).

 2.  (objection) The synopsis shows that the -x option can only be
     used with the -n option, but the options section indicates that
     it can be used both with -n and -L and is forced on with -I.  It
     also indicates that -x interacts with the size specified by a
     -s option or by the default command line size if the -s option
     is not specified.

     In fact, with sufficiently long arguments on the xargs command
     line, the -x option is needed even when -I, -L, -n, and -s are
     not specified.  Existing practice seems to be that -x is not
     tied to any of these options and should be available no matter
     what other options are specified.

xargs [-prtx] [-E eofstr|-0] [<XSI>-I replstr|-L number</XSI>|
-n number]

xargs [-prt] [-E eofstr|-0] [<XSI>-I replstr|-L number [-x]|</XSI
>-n number [-x]]

Each constructed command line shall include at least one argument from standard input. It shall be an error if a command line that will fit in the implied or specified size (see the -s option) cannot be constructed containing even one argument.

Option -x shall be forced on.

Terminate if a constructed command line will not fit in the implied or specified size (see the -s option above).

Terminate if a command line containing number arguments (see the -n option) <XSI>or number lines (see the -L option)</XSI> that will fit in the implied or specified size (see the -s option) cannot be constructed. Applications should use the -x option when it would not be appropriate for constructed commands to contain fewer than number arguments; for example, when executing the diff utility with -n 2 in order to compare pairs of files.

Editions of this standard between 2008 and 2024 did not require xargs to terminate if -x and -n number were both specified and a command line containing number arguments could not be constructed. This requirement was unintentionally lost while simplifying the description of -x. These editions continued to show (in EXAMPLES) the use of -x to force all executions of diff to be passed two operands. The requirement has now been reinstated. In addition, prior to 2008 it was unclear whether conforming XSI implementations were required to accept -x with -L number (because although this combination was described in the text, the SYNOPSIS did not require it to be accepted). Editions between 2008 and 2024 required the combination to be accepted, but with the same defect as for -x -n number. The requirements for -L now match those for -n. Some implementations accept -x with other options besides -n and -L, but there is no reason for portable applications to use such combinations and this standard does not require them to be accepted.