そして僕は途方に暮れる

case 'v':
        add_preassign(PRE_ASSIGN, optarg);
        break;

add_preassign(enum assign_type type, char *val)
{
        static long alloc_assigns;              /* for how many are allocated */

#define INIT_SRC 4

        ++numassigns;

        if (preassigns == NULL) {
                emalloc(preassigns, struct pre_assign *,
                        INIT_SRC * sizeof(struct pre_assign), "add_preassign");
                alloc_assigns = INIT_SRC;
        } else if (numassigns >= alloc_assigns) {
                alloc_assigns *= 2;
                erealloc(preassigns, struct pre_assign *,
                        alloc_assigns * sizeof(struct pre_assign), "add_preassigns");
        }
        preassigns[numassigns].type = type;
        preassigns[numassigns].val = estrdup(val, strlen(val));

#undef INIT_SRC
}

case 'F':
        add_preassign(PRE_ASSIGN_FS, optarg);
        break;

// string assignment

// POSIX disallows any newlines inside strings
// The scanner handles that for program files.
// We have to check here for strings passed to -v.
if (do_posix && strchr(cp, '\n') != NULL)
	fatal(_("POSIX does not allow physical newlines in string values"));

/*
 * BWK awk expands escapes inside assignments.
 * This makes sense, so we do it too.
 * In addition, remove \-<newline> as in scanning.
 */
it = make_str_node(cp, strlen(cp), SCAN | ELIDE_BACK_NL);
it->flags |= USER_INPUT;

if (c == '\\') {
	c = parse_escape(&pf);
	if (c < 0) {
		if (do_lint)
			lintwarn(_("backslash string continuation is not portable"));
		if ((flags & ELIDE_BACK_NL) != 0)
			continue;
		c = '\\';
	}
	*ptm++ = c;
} else
	*ptm++ = c;

parse_escape(const char **string_ptr)
{
	int c = *(*string_ptr)++;

switch (c) {
case 'a':
	return '\a';
case 'b':
	return '\b';
case 'f':
	return '\f';
case 'n':
	return '\n';
case 'r':
	return '\r';
case 't':
	return '\t';
case 'v':
	return '\v';
case '\n':
	return -2;
case 0:
	(*string_ptr)--;
	return -1;

if (*p == '\\')
{
   escape_test[ET_END].in = *++p ; /* sentinal */
   i = 0 ;
   while (escape_test[i].in != *p)  i++ ;

   if (i != ET_END)        /* in table */
   {
      p++ ;
      *q++ = escape_test[i].out ;
   }
   else if (isoctal(*p))
   {
      t = p ;
      *q++ = octal(&t) ;
      p = t ;
   }
   else if (*p == 'x' && ishex(*(unsigned char *) (p + 1)))
   {
      t = p + 1 ;
      *q++ = hex(&t) ;
      p = t ;
   }
   else if (*p == 0)        /* can only happen with command line assign */
      *q++ = '\\' ;
   else  /* not an escape sequence */
   {
      *q++ = '\\' ;
      *q++ = *p++ ;
   }
}

opt = getopt32(argv, OPTSTR_AWK, &opt_F, &list_v, &list_f, IF_FEATURE_AWK_GNU_EXTENSIONS(&list_e,) NULL);
argv += optind;
//argc -= optind;
if (opt & OPT_W)
	bb_simple_error_msg("warning: option -W is ignored");
if (opt & OPT_F) {
	unescape_string_in_place(opt_F);
	setvar_s(intvar[FS], opt_F);
}
while (list_v) {
	if (!is_assignment(llist_pop(&list_v)))
		bb_show_usage();
}

static int is_assignment(const char *expr)
{
	char *exprc, *val;

	val = (char*)endofname(expr);
	if (val == (char*)expr || *val != '=') {
		return FALSE;
	}

	exprc = xstrdup(expr);
	val = exprc + (val - expr);
	*val++ = '\0';

	unescape_string_in_place(val);
	setvar_u(newvar(exprc), val);
	free(exprc);
	return TRUE;
}

static void unescape_string_in_place(char *s1)
{
	char *s = s1;
	while ((*s1 = nextchar(&s)) != '\0')
		s1++;
}

case 'v':       /* -v a=1 to be done NOW.  one -v for each */
        vn = getarg(&argc, &argv, "no variable name");
        if (isclvar(vn))
                setclvar(vn);
        else
                FATAL("invalid -v option argument: %s", vn);
        break;

else if (c != '\\')
        *bp++ = c;
else {  /* \something */
        c = *++s;
        if (c == 0) {   /* \ at end */
                *bp++ = '\\';
                break;  /* for loop */
        }

opt = getopt32(argv, OPTSTR_AWK, &opt_F, &list_v, &list_f, IF_FEATURE_AWK_GNU_EXTENSIONS(&list_e,) NULL);

uint32_t FAST_FUNC
getopt32(char **argv, const char *applet_opts, ...)
{
	uint32_t opt;
	va_list p;

	va_start(p, applet_opts);
	opt = vgetopt32(argv, applet_opts, NULL, p);
	va_end(p);
	return opt;
}

vgetopt32(char **argv, const char *applet_opts, const char *applet_long_options, va_list p)
{
	int argc;
	unsigned flags = 0;

#if defined(LC_NUMERIC)
        /*
         * See comment above about using locale's decimal point.
         *
         * 10/2005:
         * Bitter experience teaches us that most people the world over
         * use period as the decimal point, not whatever their locale
         * uses.  Thus, only use the locale's decimal point if being
         * posixly anal-retentive.
         *
         * 7/2007:
         * Be a little bit kinder. Allow the --use-lc-numeric option
         * to also use the local decimal point. This avoids the draconian
         * strictness of POSIX mode if someone just wants to parse their
         * data using the local decimal point.
         */
        if (use_lc_numeric)
                setlocale(LC_NUMERIC, locale);
#endif

diff --git a/NEWS b/NEWS
index 39a0903..4a62fb7 100644
--- a/NEWS
+++ b/NEWS
@@ -2,6 +2,11 @@ GNU grep NEWS                                    -*- outline -*-
 
 * Noteworthy changes in release ?.? (????-??-??) [?]
 
+** Changes in behavior
+
+  The egrep and fgrep commands, which have been deprecated since
+  release 2.5.3 (2007), now warn that they are obsolescent and should
+  be replaced by grep -E and grep -F.
 
 * Noteworthy changes in release 3.7 (2021-08-14) [stable]
 
diff --git a/doc/grep.in.1 b/doc/grep.in.1
index e8854f2..b014f65 100644
--- a/doc/grep.in.1
+++ b/doc/grep.in.1
@@ -137,7 +137,7 @@
 .hy 0
 .
 .SH NAME
-grep, egrep, fgrep \- print lines that match patterns
+grep \- print lines that match patterns
 .
 .SH SYNOPSIS
 .B grep
@@ -184,17 +184,6 @@ If no
 .I FILE
 is given, recursive searches examine the working directory,
 and nonrecursive searches read standard input.
-.PP
-In addition, the variant programs
-.B egrep
-and
-.B fgrep
-are the same as
-.B "grep\ \-E"
-and
-.BR "grep\ \-F" ,
-respectively.
-These variants are deprecated, but are provided for backward compatibility.
 .
 .SH OPTIONS
 .SS "Generic Program Information"
diff --git a/doc/grep.texi b/doc/grep.texi
index 63d2fc9..3236b98 100644
--- a/doc/grep.texi
+++ b/doc/grep.texi
@@ -1159,15 +1159,6 @@ combined with the @option{-z} (@option{--null-data}) option, and note that
 
 @end table
 
-In addition,
-two variant programs @command{egrep} and @command{fgrep} are available.
-@command{egrep} is the same as @samp{grep@ -E}.
-@command{fgrep} is the same as @samp{grep@ -F}.
-Direct invocation as either
-@command{egrep} or @command{fgrep} is deprecated,
-but is provided to allow historical applications
-that rely on them to run unmodified.
-
 
 @node Regular Expressions
 @chapter Regular Expressions
@@ -1918,7 +1909,7 @@ before giving it to @command{grep}, or turn to @command{awk},
 designed to operate across lines.
 
 @item
-What do @command{grep}, @command{fgrep}, and @command{egrep} stand for?
+What do @command{grep}, @option{-E}, and @option{-F} stand for?
 
 The name @command{grep} comes from the way line editing was done on Unix.
 For example,
@@ -1930,8 +1921,29 @@ global/regular expression/print
 g/re/p
 @end example
 
-@command{fgrep} stands for Fixed @command{grep};
-@command{egrep} stands for Extended @command{grep}.
+The @option{-E} option stands for Extended @command{grep}.
+The @option{-F} option stands for Fixed @command{grep};
+
+@item
+What happened to @command{egrep} and @command{fgrep}?
+
+7th Edition Unix had commands @command{egrep} and @command{fgrep}
+that were the counterparts of the modern @samp{grep -E} and @samp{grep -F}.
+Although breaking up @command{grep} into three programs was perhaps
+useful on the small computers of the 1970s, @command{egrep} and
+@command{fgrep} were not standardized by POSIX and are no longer needed.
+In the current GNU implementation, @command{egrep} and @command{fgrep}
+issue a warning and then act like their modern counterparts;
+eventually, they are planned to be removed entirely.
+
+If you prefer the old names, you can use use your own substitutes,
+such as a shell script named @command{egrep} with the following
+contents:
+
+@example
+#!/bin/sh
+exec grep -E "$@@"
+@end example
 
 @end enumerate
 
diff --git a/src/egrep.sh b/src/egrep.sh
index 6d6c15a..a0d1694 100644
--- a/src/egrep.sh
+++ b/src/egrep.sh
@@ -1,2 +1,4 @@
 #!@SHELL@
+cmd=${0##*/}
+echo "$cmd: warning: $cmd is obsolescent; using @grep@ @option@" >&2
 exec @grep@ @option@ "$@"

int
main (int argc, char **argv)
{
  char *keys;
  size_t keycc, oldcc, keyalloc;
  int with_filenames;
  int opt, cc, status;
  int default_context;
  FILE *fp;
  extern char *optarg;
  extern int optind;

  initialize_main (&argc, &argv);
  program_name = argv[0];
  if (program_name && strrchr (program_name, '/'))
    program_name = strrchr (program_name, '/') + 1;

  if (!strcmp(program_name, "egrep"))
    setmatcher ("egrep");
  if (!strcmp(program_name, "fgrep"))
    setmatcher ("fgrep");

#define EGREP_PROGRAM
#include "grep.c"

#define FGREP_PROGRAM
#include "grep.c"

#define EGREP_PROGRAM
#include "search.c"

#define FGREP_PROGRAM
#include "search.c"

#!@SHELL@
grep=grep
case $0 in
  */*)
    dir=${0%/*}
    if test -x "$dir/@grep@"; then
      PATH=$dir:$PATH
      grep=@grep@
    fi;;
esac
exec $grep @option@ "$@"