05-29-2008
Quote:
Double quotes don't prevent variables from being expanded locally. So the remote host sees "ITSME=itsyou; echo itsme" in the first case.
So the two statements: ITSME=itsyou & echo $ITSME are both executed on remote host. But in the case of double quotes, variable will be evaluated first so the argument passed to ssh is actually ITSME=itsyou; echo itsme. While in the case of single quotes, no special characters survive. The argument passed to ssh is ITSME=itsyou; echo $ITSME. Understood, this is really an issue of command-line processing.
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XARGS(1) General Commands Manual XARGS(1)
NAME
xargs - construct argument list(s) and execute utility
SYNOPSIS
xargs [ -t ][[ -x ] -n number ][ -s size ][ utility [ arguments... ]]
DESCRIPTION
The xargs utility reads space, tab, newline and end-of-file delimited arguments from the standard input and executes the specified utility
with them as arguments.
The utility and any arguments specified on the command line are given to the utility upon each invocation, followed by some number of the
arguments read from standard input. The utility is repeatedly executed until standard input is exhausted.
Spaces, tabs and newlines may be embedded in arguments using single (`` ' '') or double (``"'') quotes or backslashes (``''). Single
quotes escape all non-single quote characters, excluding newlines, up to the matching single quote. Double quotes escape all non-double
quote characters, excluding newlines, up to the matching double quote. Any single character, including newlines, may be escaped by a back-
slash.
The options are as follows:
-n number Set the maximum number of arguments taken from standard input for each invocation of the utility. An invocation of utility will
use less than number standard input arguments if the number of bytes accumulated (see the s option) exceeds the specified size or
there are fewer than number arguments remaining for the last invocation of utility. The current default value for number is
5000.
-s size Set the maximum number of bytes for the command line length provided to utility. The sum of the length of the utility name and
the arguments passed to utility (including /dev/null terminators) will be less than or equal to this number. The current default
value for size is ARG_MAX - 2048.
-t Echo the command to be executed to standard error immediately before it is executed.
-x Force xargs to terminate immediately if a command line containing number arguments will not fit in the specified (or default)
command line length.
If no utility is specified, echo(1) is used.
Undefined behavior may occur if utility reads from the standard input.
The xargs utility exits immediately (without processing any further input) if a command line cannot be assembled, utility cannot be
invoked, an invocation of the utility is terminated by a signal or an invocation of the utility exits with a value of 255.
The xargs utility exits with a value of 0 if no error occurs. If utility cannot be invoked, xargs exits with a value of 127. If any other
error occurs, xargs exits with a value of 1.
SEE ALSO
echo(1), find(1)
STANDARDS
The xargs utility is expected to be IEEE Std 1003.2("POSIX") compliant.
June 6, 1993 XARGS(1)