sources-request@panda.UUCP (02/06/86)
Mod.sources: Volume 3, Issue 106
Submitted by: seismo!amdahl!gam (Gordon A. Moffett)
Here is a reimplementation of the System V utility xargs. I haven't
heard any complaints about it, though [1] There is room for improvement
regarding the command buffer size (tho' it is better than the System V
area in that particular regard) [2] It does not have all the features
of the System V version (as the man page points out).
Gordon A. Moffett
{ihnp4,seismo,hplabs}!amdahl!gam
--------------------------------------------------------------------
# This is a shell archive. Remove anything before this line,
# then unpack it by saving it in a file and typing "sh file".
#
# Wrapped by gam on Wed Feb 5 13:15:01 PST 1986
# Contents: xargs.1 xargs.c
echo x - xargs.1
sed 's/^@//' > "xargs.1" <<'@//E*O*F xargs.1//'
@.TH XARGS 1
@.SH NAME
xargs \- execute a command with many arguments
@.SH SYNOPSIS
@.B xargs
command ...
@.SH DESCRIPTION
@.I Xargs
is based on the System V command of the same name. This
version performs the default function of
@.IR xargs ,
which is also the simplest function.
@.PP
Because Unix imposes a limit on how much space the arguments
of a command may use, that if the argument list were too
large the system prohibits the
command from being executed (in System V, this error is
@.BR E2BIG ,
@.B errno
= 7).
@.PP
To avoid this problem,
@.I xargs
will take arguments which are themselves a command and
@.I its
arguments (options), and then read standard input and
apply it to the command with its given arguments.
@.I Xargs
is careful not to excede the system-imposed limit, which
is expected to be greater than the system's stream file
buffer size,
@.B BUFSIZ
in
@.IR /usr/include/stdio.h .
(The true upper limit can be found in the manual page
@.IR intro(2),
where the
@.B E2BIG
error is described).
It continues to execute the command with the read-in arguments
until it reaches end-of-file.
@.SH "SEE ALSO"
intro(2), exec(2)
@.SH BUGS
Not really the System V Release 2 version at all, but just
looks like it.
@.SH NOTES
@//E*O*F xargs.1//
chmod u=rw,g=r,o=r xargs.1
echo x - xargs.c
sed 's/^@//' > "xargs.c" <<'@//E*O*F xargs.c//'
/* xargs -- quickie version of System V xargs(1): read a list of
* arguments from stdin, apply to the command which is
* the argument(s) of xargs
*/
#include <stdio.h>
char *cmdname; /* should point to argv[0] */
char command[BUFSIZ]; /* command given to xargs */
char line[BUFSIZ]; /* current input line */
char cmdbuf[BUFSIZ]; /* command + input lines */
main(argc, argv)
int argc;
char *argv[];
{
char *gets();
char *strcat(), *strcpy();
cmdname = argv[0];
/* skip (xargs) command name */
argv++, argc--;
/* construct command from arguments */
strcpy(command, "exec");
while (argc--) {
(void) strcat(command, " ");
(void) strcat(command, *argv++);
}
/* initialize for command execution loop */
(void) strcpy(cmdbuf, command);
/* here's where all the action is: read in arguments
* from stdin, appending to the current command buffer
* if next line would overflow command buffer, execute
* command buffer and reinitialize
*/
while (gets(line) != NULL) {
/* the "+2" is for the blank and trailing null char */
if (strlen(cmdbuf)+strlen(line)+2 > BUFSIZ) {
docmd(cmdbuf);
(void) strcpy(cmdbuf, command);
}
(void) strcat(cmdbuf, " ");
(void) strcat(cmdbuf, line);
}
/* see if there is any left to do */
if (strlen(cmdbuf) != strlen(command)) {
docmd(cmdbuf);
}
}
docmd(cmdbuf)
char *cmdbuf;
{
return system(cmdbuf);
}
@//E*O*F xargs.c//
chmod u=rw,g=r,o=r xargs.c
exit 0