Adding seq command.

LICENSE

@@ -8,6 +8,8 @@ MIT/X Consortium License
 © 2011 pancake <pancake@youterm.com>
 © 2011 Random832 <random832@fastmail.us>
 © 2012 William Haddon <william@haddonthethird.net>
+© 2012 Kurt H. Maier <khm@intma.in>
+© 2012 Christoph Lohmann <20h@r-36.net> 
 
 Permission is hereby granted, free of charge, to any person obtaining a
 copy of this software and associated documentation files (the "Software"),

Makefile

@@ -51,6 +51,7 @@ SRC = \
 	true.c     \
 	tty.c      \
 	uname.c    \
+	seq.c      \
 	wc.c
 
 OBJ = $(SRC:.c=.o) $(LIB)

seq.c

@@ -0,0 +1,167 @@
+/* See LICENSE file for copyright and license details. */
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <unistd.h>
+#include <stdbool.h>
+#include <libgen.h>
+
+#include "util.h"
+
+char afmt[4096];
+
+char *
+getalignedwidthfmt(char *fmt, char *starts, char *steps, char *ends)
+{
+  char starttmp[4096], steptmp[4096], endtmp[4096];
+  char *startdelim, *stepdelim, *enddelim;
+  int startl, startr, stepr, endl, endr;
+  int maxl, maxr;
+
+  /*
+   * 1.) Get a temp buffer we can work in.
+   * 2.) Calculate the *r(ight) and *l(eft) size.
+   */
+  memmove(starttmp, starts, strlen(starts)+1);
+  startdelim = strchr(starttmp, '.');
+  if (startdelim != NULL) {
+    startdelim[0] = '\0';
+    startr = strlen(startdelim+1);
+  } else {
+    startr = 0;
+  }
+  startl = strlen(starttmp);
+  if (starttmp[0] == '+')
+    startl--;
+
+  memmove(endtmp, ends, strlen(ends)+1);
+  enddelim = strchr(endtmp, '.');
+  if (enddelim != NULL) {
+    enddelim[0] = '\0';
+    endr = strlen(enddelim+1);
+  } else {
+    endr = 0;
+  }
+  endl = strlen(endtmp);
+  if (endtmp[0] == '+')
+    endl--;
+
+  /*
+   * We do not care for the left length of the step, because it
+   * will never be displayed.
+   */
+  memmove(steptmp, steps, strlen(steps)+1);
+  stepdelim = strchr(steptmp, '.');
+  if (stepdelim != NULL) {
+    stepdelim[0] = '\0';
+    stepr = strlen(stepdelim+1);
+  } else {
+    stepr = 0;
+  }
+
+  maxl = (startl > endl)? startl : endl;
+  maxr = (startl > endr)? startr : endr;
+  if (stepr > maxr)
+    maxr = stepr;
+
+  if (maxl <= 1) {
+    snprintf(afmt, sizeof(afmt), "%%.%df", maxr);
+  } else if (maxr == 0) {
+    snprintf(afmt, sizeof(afmt), "%%0%d.f", maxl);
+  } else {
+    snprintf(afmt, sizeof(afmt), "%%0%d.%df", maxl+maxr+1, maxr);
+  }
+
+  return afmt;
+}
+
+int
+main(int argc, char *argv[])
+{
+  char c, *fmt, *sep, *starts, *steps, *ends;
+  bool wflag = false;
+  double start, step, end, out;
+
+  sep = "\n";
+  fmt = "%G";
+
+  starts = "1";
+  steps = "1";
+  ends = "1";
+
+  while((c = getopt(argc, argv, "f:s:w")) != -1) {
+    switch(c) {
+      case 'f':
+        fmt = optarg;
+        break;
+      case 's':
+        sep = optarg;
+        break;
+      case 'w':
+        wflag = true;
+        break;
+    }
+  }
+
+  switch(argc-optind) {
+    case 3:
+      starts = argv[optind++];
+      steps = argv[optind++];
+      ends = argv[optind++];
+      break;
+    case 2:
+      starts = argv[optind++];
+      ends = argv[optind++];
+      break;
+    case 1:
+      ends = argv[optind++];
+      break;
+    default:
+      eprintf("usage: %s [-f fmt] [-s separator] [-w] [start [step]]"
+		     " end\n", basename(argv[0]));
+  }
+
+  start = atof(starts);
+  step = atof(steps);
+  end = atof(ends);
+
+  if (step == 0)
+    return EXIT_FAILURE;
+
+  if (start > end) {
+    if (step > 0)
+      return EXIT_FAILURE;
+  } else if (start < end) {
+    if (step < 0)
+      return EXIT_FAILURE;
+  }
+
+  if (wflag)
+    fmt = getalignedwidthfmt(fmt, starts, steps, ends);
+  printf("%s\n", fmt);
+
+  for (out = start;;) {
+    printf(fmt, out);
+
+    out += step;
+    if (start > end) {
+      if (out >= end) {
+        printf("%s", sep);
+      } else {
+        break;
+      }
+    } else if (start < end) {
+      if (out <= end) {
+        printf("%s", sep);
+      } else {
+        break;
+      }
+    } else {
+      break;
+    }
+  }
+  printf("\n");
+
+  return EXIT_SUCCESS;
+}
+