view toys/posix/who.c @ 1531:3ff823086c99 draft

Teach ln -f to leave original target alone if link creation fails. Suggested by Ashwini Sharma, I wound up implementing it by creating the new link at a temporary name and renaming it over the old one instead of renaming the old file out of the way and putting it back if it failed. (Because "mkdir -p one/one/blah && ln -sf /bin/one one" would otherwise rename one/one out of the way and only notice it can't delete it way at the end when recovery's darn awkward, vs create new thing and if rename fails (including EISDIR) that's the main error path. And yes the temporary name is in the same directory as the destination so we never rename between mounts.) link over the old one instead of renaming the old file and renaming it back.
author Rob Landley <rob@landley.net>
date Wed, 22 Oct 2014 17:11:06 -0500
parents 53f165466f3b
children 685a0da6ca59
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/* who.c - display who is on the system
 *
 * Copyright 2012 ProFUSION Embedded Systems
 *
 * by Luis Felipe Strano Moraes <lfelipe@profusion.mobi>
 *
 * See http://opengroup.org/onlinepubs/9699919799/utilities/who.html
 *
 * Posix says to support many options (-abdHlmpqrstTu) but this
 * isn't aimed at minicomputers with modem pools.

USE_WHO(NEWTOY(who, "a", TOYFLAG_BIN))

config WHO
  bool "who"
  default y
  help
    usage: who

    Print logged user information on system
*/

#define FOR_who
#include "toys.h"

void who_main(void)
{
  struct utmpx *entry;

  setutxent();

  while ((entry = getutxent())) {
    if ((toys.optflags & FLAG_a) || entry->ut_type == USER_PROCESS) {
      time_t time;
      int time_size;
      char *times;

      time = entry->ut_tv.tv_sec;
      times = ctime(&time);
      time_size = strlen(times) - 2;
      printf("%s\t%s\t%*.*s\t(%s)\n", entry->ut_user, entry->ut_line,
        time_size, time_size, ctime(&time), entry->ut_host);
    }
  }

  endutxent();
}