From abc0f4f8f97b36f2865986374405d091cefea107 Mon Sep 17 00:00:00 2001 From: Eric Andersen Date: Wed, 8 Dec 1999 23:19:36 +0000 Subject: Latest and greatest --- tail.c | 955 +++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 955 insertions(+) create mode 100644 tail.c (limited to 'tail.c') diff --git a/tail.c b/tail.c new file mode 100644 index 000000000..058d462a5 --- /dev/null +++ b/tail.c @@ -0,0 +1,955 @@ +/* tail -- output the last part of file(s) + Copyright (C) 89, 90, 91, 95, 1996 Free Software Foundation, Inc. + + This program is free software; you can redistribute it and/or modify + it under the terms of the GNU General Public License as published by + the Free Software Foundation; either version 2, or (at your option) + any later version. + + This program is distributed in the hope that it will be useful, + but WITHOUT ANY WARRANTY; without even the implied warranty of + MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the + GNU General Public License for more details. + + You should have received a copy of the GNU General Public License + along with this program; if not, write to the Free Software + Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA. */ + +/* Can display any amount of data, unlike the Unix version, which uses + a fixed size buffer and therefore can only deliver a limited number + of lines. + + Options: + -b Tail by N 512-byte blocks. + -c, --bytes=N[bkm] Tail by N bytes + [or 512-byte blocks, kilobytes, or megabytes]. + -f, --follow Loop forever trying to read more characters at the + end of the file, on the assumption that the file + is growing. Ignored if reading from a pipe. + -n, --lines=N Tail by N lines. + -q, --quiet, --silent Never print filename headers. + -v, --verbose Always print filename headers. + + If a number (N) starts with a `+', begin printing with the Nth item + from the start of each file, instead of from the end. + + Reads from standard input if no files are given or when a filename of + ``-'' is encountered. + By default, filename headers are printed only more than one file + is given. + By default, prints the last 10 lines (tail -n 10). + + Original version by Paul Rubin . + Extensions by David MacKenzie . + tail -f for multiple files by Ian Lance Taylor . */ + +#include "internal.h" + +#include +#include +#include +#include + + +/* Disable assertions. Some systems have broken assert macros. */ +#define NDEBUG 1 + + +static void error(int i, int errnum, char* fmt, const char *msg) +{ + fprintf(stderr, fmt, msg); + perror( errnum); + exit(i); +} + + +#define XWRITE(fd, buffer, n_bytes) \ + do \ + { \ + assert ((fd) == 1); \ + assert ((n_bytes) >= 0); \ + if (n_bytes > 0 && fwrite ((buffer), 1, (n_bytes), stdout) == 0) \ + error (EXIT_FAILURE, errno, "write error", NULL); \ + } \ + while (0) + +/* Number of items to tail. */ +#define DEFAULT_N_LINES 10 + +/* Size of atomic reads. */ +#ifndef BUFSIZ +#define BUFSIZ (512 * 8) +#endif + +/* If nonzero, interpret the numeric argument as the number of lines. + Otherwise, interpret it as the number of bytes. */ +static int count_lines; + +/* If nonzero, read from the end of one file until killed. */ +static int forever; + +/* If nonzero, read from the end of multiple files until killed. */ +static int forever_multiple; + +/* Array of file descriptors if forever_multiple is 1. */ +static int *file_descs; + +/* Array of file sizes if forever_multiple is 1. */ +static off_t *file_sizes; + +/* If nonzero, count from start of file instead of end. */ +static int from_start; + +/* If nonzero, print filename headers. */ +static int print_headers; + +/* When to print the filename banners. */ +enum header_mode +{ + multiple_files, always, never +}; + +char *xmalloc (); +int safe_read (); + +/* The name this program was run with. */ +char *program_name; + +/* Nonzero if we have ever read standard input. */ +static int have_read_stdin; + +/* If nonzero, display usage information and exit. */ +static int show_help; + +/* If nonzero, print the version on standard output then exit. */ +static int show_version; + +static const char tail_usage[] = +"tail [OPTION]... [FILE]...\n\ +Print last 10 lines of each FILE to standard output.\n\ +With more than one FILE, precede each with a header giving the file name.\n\ +With no FILE, or when FILE is -, read standard input.\n\ +\n\ + -c, --bytes=N output the last N bytes\n\ + -f, --follow output appended data as the file grows\n\ + -n, --lines=N output the last N lines, instead of last 10\n\ + -q, --quiet, --silent never output headers giving file names\n\ + -v, --verbose always output headers giving file names\n\ + --help display this help and exit\n\ + --version output version information and exit\n\ +\n\ +If the first character of N (the number of bytes or lines) is a `+',\n\ +print beginning with the Nth item from the start of each file, otherwise,\n\ +print the last N items in the file. N may have a multiplier suffix:\n\ +b for 512, k for 1024, m for 1048576 (1 Meg). A first OPTION of -VALUE\n\ +or +VALUE is treated like -n VALUE or -n +VALUE unless VALUE has one of\n\ +the [bkm] suffix multipliers, in which case it is treated like -c VALUE\n\ +or -c +VALUE.\n"; + +static void +write_header (const char *filename, const char *comment) +{ + static int first_file = 1; + + printf ("%s==> %s%s%s <==\n", (first_file ? "" : "\n"), filename, + (comment ? ": " : ""), + (comment ? comment : "")); + first_file = 0; +} + +/* Print the last N_LINES lines from the end of file FD. + Go backward through the file, reading `BUFSIZ' bytes at a time (except + probably the first), until we hit the start of the file or have + read NUMBER newlines. + POS starts out as the length of the file (the offset of the last + byte of the file + 1). + Return 0 if successful, 1 if an error occurred. */ + +static int +file_lines (const char *filename, int fd, long int n_lines, off_t pos) +{ + char buffer[BUFSIZ]; + int bytes_read; + int i; /* Index into `buffer' for scanning. */ + + if (n_lines == 0) + return 0; + + /* Set `bytes_read' to the size of the last, probably partial, buffer; + 0 < `bytes_read' <= `BUFSIZ'. */ + bytes_read = pos % BUFSIZ; + if (bytes_read == 0) + bytes_read = BUFSIZ; + /* Make `pos' a multiple of `BUFSIZ' (0 if the file is short), so that all + reads will be on block boundaries, which might increase efficiency. */ + pos -= bytes_read; + lseek (fd, pos, SEEK_SET); + bytes_read = safe_read (fd, buffer, bytes_read); + if (bytes_read == -1) + { + error (0, errno, "%s", filename); + return 1; + } + + /* Count the incomplete line on files that don't end with a newline. */ + if (bytes_read && buffer[bytes_read - 1] != '\n') + --n_lines; + + do + { + /* Scan backward, counting the newlines in this bufferfull. */ + for (i = bytes_read - 1; i >= 0; i--) + { + /* Have we counted the requested number of newlines yet? */ + if (buffer[i] == '\n' && n_lines-- == 0) + { + /* If this newline wasn't the last character in the buffer, + print the text after it. */ + if (i != bytes_read - 1) + XWRITE (STDOUT_FILENO, &buffer[i + 1], bytes_read - (i + 1)); + return 0; + } + } + /* Not enough newlines in that bufferfull. */ + if (pos == 0) + { + /* Not enough lines in the file; print the entire file. */ + lseek (fd, (off_t) 0, SEEK_SET); + return 0; + } + pos -= BUFSIZ; + lseek (fd, pos, SEEK_SET); + } + while ((bytes_read = safe_read (fd, buffer, BUFSIZ)) > 0); + if (bytes_read == -1) + { + error (0, errno, "%s", filename); + return 1; + } + return 0; +} + +/* Print the last N_LINES lines from the end of the standard input, + open for reading as pipe FD. + Buffer the text as a linked list of LBUFFERs, adding them as needed. + Return 0 if successful, 1 if an error occured. */ + +static int +pipe_lines (const char *filename, int fd, long int n_lines) +{ + struct linebuffer + { + int nbytes, nlines; + char buffer[BUFSIZ]; + struct linebuffer *next; + }; + typedef struct linebuffer LBUFFER; + LBUFFER *first, *last, *tmp; + int i; /* Index into buffers. */ + int total_lines = 0; /* Total number of newlines in all buffers. */ + int errors = 0; + + first = last = (LBUFFER *) xmalloc (sizeof (LBUFFER)); + first->nbytes = first->nlines = 0; + first->next = NULL; + tmp = (LBUFFER *) xmalloc (sizeof (LBUFFER)); + + /* Input is always read into a fresh buffer. */ + while ((tmp->nbytes = safe_read (fd, tmp->buffer, BUFSIZ)) > 0) + { + tmp->nlines = 0; + tmp->next = NULL; + + /* Count the number of newlines just read. */ + for (i = 0; i < tmp->nbytes; i++) + if (tmp->buffer[i] == '\n') + ++tmp->nlines; + total_lines += tmp->nlines; + + /* If there is enough room in the last buffer read, just append the new + one to it. This is because when reading from a pipe, `nbytes' can + often be very small. */ + if (tmp->nbytes + last->nbytes < BUFSIZ) + { + memcpy (&last->buffer[last->nbytes], tmp->buffer, tmp->nbytes); + last->nbytes += tmp->nbytes; + last->nlines += tmp->nlines; + } + else + { + /* If there's not enough room, link the new buffer onto the end of + the list, then either free up the oldest buffer for the next + read if that would leave enough lines, or else malloc a new one. + Some compaction mechanism is possible but probably not + worthwhile. */ + last = last->next = tmp; + if (total_lines - first->nlines > n_lines) + { + tmp = first; + total_lines -= first->nlines; + first = first->next; + } + else + tmp = (LBUFFER *) xmalloc (sizeof (LBUFFER)); + } + } + if (tmp->nbytes == -1) + { + error (0, errno, "%s", filename); + errors = 1; + free ((char *) tmp); + goto free_lbuffers; + } + + free ((char *) tmp); + + /* This prevents a core dump when the pipe contains no newlines. */ + if (n_lines == 0) + goto free_lbuffers; + + /* Count the incomplete line on files that don't end with a newline. */ + if (last->buffer[last->nbytes - 1] != '\n') + { + ++last->nlines; + ++total_lines; + } + + /* Run through the list, printing lines. First, skip over unneeded + buffers. */ + for (tmp = first; total_lines - tmp->nlines > n_lines; tmp = tmp->next) + total_lines -= tmp->nlines; + + /* Find the correct beginning, then print the rest of the file. */ + if (total_lines > n_lines) + { + char *cp; + + /* Skip `total_lines' - `n_lines' newlines. We made sure that + `total_lines' - `n_lines' <= `tmp->nlines'. */ + cp = tmp->buffer; + for (i = total_lines - n_lines; i; --i) + while (*cp++ != '\n') + /* Do nothing. */ ; + i = cp - tmp->buffer; + } + else + i = 0; + XWRITE (STDOUT_FILENO, &tmp->buffer[i], tmp->nbytes - i); + + for (tmp = tmp->next; tmp; tmp = tmp->next) + XWRITE (STDOUT_FILENO, tmp->buffer, tmp->nbytes); + +free_lbuffers: + while (first) + { + tmp = first->next; + free ((char *) first); + first = tmp; + } + return errors; +} + +/* Print the last N_BYTES characters from the end of pipe FD. + This is a stripped down version of pipe_lines. + Return 0 if successful, 1 if an error occurred. */ + +static int +pipe_bytes (const char *filename, int fd, off_t n_bytes) +{ + struct charbuffer + { + int nbytes; + char buffer[BUFSIZ]; + struct charbuffer *next; + }; + typedef struct charbuffer CBUFFER; + CBUFFER *first, *last, *tmp; + int i; /* Index into buffers. */ + int total_bytes = 0; /* Total characters in all buffers. */ + int errors = 0; + + first = last = (CBUFFER *) xmalloc (sizeof (CBUFFER)); + first->nbytes = 0; + first->next = NULL; + tmp = (CBUFFER *) xmalloc (sizeof (CBUFFER)); + + /* Input is always read into a fresh buffer. */ + while ((tmp->nbytes = safe_read (fd, tmp->buffer, BUFSIZ)) > 0) + { + tmp->next = NULL; + + total_bytes += tmp->nbytes; + /* If there is enough room in the last buffer read, just append the new + one to it. This is because when reading from a pipe, `nbytes' can + often be very small. */ + if (tmp->nbytes + last->nbytes < BUFSIZ) + { + memcpy (&last->buffer[last->nbytes], tmp->buffer, tmp->nbytes); + last->nbytes += tmp->nbytes; + } + else + { + /* If there's not enough room, link the new buffer onto the end of + the list, then either free up the oldest buffer for the next + read if that would leave enough characters, or else malloc a new + one. Some compaction mechanism is possible but probably not + worthwhile. */ + last = last->next = tmp; + if (total_bytes - first->nbytes > n_bytes) + { + tmp = first; + total_bytes -= first->nbytes; + first = first->next; + } + else + { + tmp = (CBUFFER *) xmalloc (sizeof (CBUFFER)); + } + } + } + if (tmp->nbytes == -1) + { + error (0, errno, "%s", filename); + errors = 1; + free ((char *) tmp); + goto free_cbuffers; + } + + free ((char *) tmp); + + /* Run through the list, printing characters. First, skip over unneeded + buffers. */ + for (tmp = first; total_bytes - tmp->nbytes > n_bytes; tmp = tmp->next) + total_bytes -= tmp->nbytes; + + /* Find the correct beginning, then print the rest of the file. + We made sure that `total_bytes' - `n_bytes' <= `tmp->nbytes'. */ + if (total_bytes > n_bytes) + i = total_bytes - n_bytes; + else + i = 0; + XWRITE (STDOUT_FILENO, &tmp->buffer[i], tmp->nbytes - i); + + for (tmp = tmp->next; tmp; tmp = tmp->next) + XWRITE (STDOUT_FILENO, tmp->buffer, tmp->nbytes); + +free_cbuffers: + while (first) + { + tmp = first->next; + free ((char *) first); + first = tmp; + } + return errors; +} + +/* Skip N_BYTES characters from the start of pipe FD, and print + any extra characters that were read beyond that. + Return 1 on error, 0 if ok. */ + +static int +start_bytes (const char *filename, int fd, off_t n_bytes) +{ + char buffer[BUFSIZ]; + int bytes_read = 0; + + while (n_bytes > 0 && (bytes_read = safe_read (fd, buffer, BUFSIZ)) > 0) + n_bytes -= bytes_read; + if (bytes_read == -1) + { + error (0, errno, "%s", filename); + return 1; + } + else if (n_bytes < 0) + XWRITE (STDOUT_FILENO, &buffer[bytes_read + n_bytes], -n_bytes); + return 0; +} + +/* Skip N_LINES lines at the start of file or pipe FD, and print + any extra characters that were read beyond that. + Return 1 on error, 0 if ok. */ + +static int +start_lines (const char *filename, int fd, long int n_lines) +{ + char buffer[BUFSIZ]; + int bytes_read = 0; + int bytes_to_skip = 0; + + while (n_lines && (bytes_read = safe_read (fd, buffer, BUFSIZ)) > 0) + { + bytes_to_skip = 0; + while (bytes_to_skip < bytes_read) + if (buffer[bytes_to_skip++] == '\n' && --n_lines == 0) + break; + } + if (bytes_read == -1) + { + error (0, errno, "%s", filename); + return 1; + } + else if (bytes_to_skip < bytes_read) + { + XWRITE (STDOUT_FILENO, &buffer[bytes_to_skip], + bytes_read - bytes_to_skip); + } + return 0; +} + +/* Display file FILENAME from the current position in FD to the end. + If `forever' is nonzero, keep reading from the end of the file + until killed. Return the number of bytes read from the file. */ + +static long +dump_remainder (const char *filename, int fd) +{ + char buffer[BUFSIZ]; + int bytes_read; + long total; + + total = 0; +output: + while ((bytes_read = safe_read (fd, buffer, BUFSIZ)) > 0) + { + XWRITE (STDOUT_FILENO, buffer, bytes_read); + total += bytes_read; + } + if (bytes_read == -1) + error (EXIT_FAILURE, errno, "%s", filename); + if (forever) + { + fflush (stdout); + sleep (1); + goto output; + } + else + { + if (forever_multiple) + fflush (stdout); + } + + return total; +} + +/* Tail NFILES (>1) files forever until killed. The file names are in + NAMES. The open file descriptors are in `file_descs', and the size + at which we stopped tailing them is in `file_sizes'. We loop over + each of them, doing an fstat to see if they have changed size. If + none of them have changed size in one iteration, we sleep for a + second and try again. We do this until the user interrupts us. */ + +static void +tail_forever (char **names, int nfiles) +{ + int last; + + last = -1; + + while (1) + { + int i; + int changed; + + changed = 0; + for (i = 0; i < nfiles; i++) + { + struct stat stats; + + if (file_descs[i] < 0) + continue; + if (fstat (file_descs[i], &stats) < 0) + { + error (0, errno, "%s", names[i]); + file_descs[i] = -1; + continue; + } + if (stats.st_size == file_sizes[i]) + continue; + + /* This file has changed size. Print out what we can, and + then keep looping. */ + + changed = 1; + + if (stats.st_size < file_sizes[i]) + { + write_header (names[i], "file truncated"); + last = i; + lseek (file_descs[i], stats.st_size, SEEK_SET); + file_sizes[i] = stats.st_size; + continue; + } + + if (i != last) + { + if (print_headers) + write_header (names[i], NULL); + last = i; + } + file_sizes[i] += dump_remainder (names[i], file_descs[i]); + } + + /* If none of the files changed size, sleep. */ + if (! changed) + sleep (1); + } +} + +/* Output the last N_BYTES bytes of file FILENAME open for reading in FD. + Return 0 if successful, 1 if an error occurred. */ + +static int +tail_bytes (const char *filename, int fd, off_t n_bytes) +{ + struct stat stats; + + /* FIXME: resolve this like in dd.c. */ + /* Use fstat instead of checking for errno == ESPIPE because + lseek doesn't work on some special files but doesn't return an + error, either. */ + if (fstat (fd, &stats)) + { + error (0, errno, "%s", filename); + return 1; + } + + if (from_start) + { + if (S_ISREG (stats.st_mode)) + lseek (fd, n_bytes, SEEK_CUR); + else if (start_bytes (filename, fd, n_bytes)) + return 1; + dump_remainder (filename, fd); + } + else + { + if (S_ISREG (stats.st_mode)) + { + off_t current_pos, end_pos; + size_t bytes_remaining; + + if ((current_pos = lseek (fd, (off_t) 0, SEEK_CUR)) != -1 + && (end_pos = lseek (fd, (off_t) 0, SEEK_END)) != -1) + { + off_t diff; + /* Be careful here. The current position may actually be + beyond the end of the file. */ + bytes_remaining = (diff = end_pos - current_pos) < 0 ? 0 : diff; + } + else + { + error (0, errno, "%s", filename); + return 1; + } + + if (bytes_remaining <= n_bytes) + { + /* From the current position to end of file, there are no + more bytes than have been requested. So reposition the + file pointer to the incoming current position and print + everything after that. */ + lseek (fd, current_pos, SEEK_SET); + } + else + { + /* There are more bytes remaining than were requested. + Back up. */ + lseek (fd, -n_bytes, SEEK_END); + } + dump_remainder (filename, fd); + } + else + return pipe_bytes (filename, fd, n_bytes); + } + return 0; +} + +/* Output the last N_LINES lines of file FILENAME open for reading in FD. + Return 0 if successful, 1 if an error occurred. */ + +static int +tail_lines (const char *filename, int fd, long int n_lines) +{ + struct stat stats; + off_t length; + + if (fstat (fd, &stats)) + { + error (0, errno, "%s", filename); + return 1; + } + + if (from_start) + { + if (start_lines (filename, fd, n_lines)) + return 1; + dump_remainder (filename, fd); + } + else + { + /* Use file_lines only if FD refers to a regular file with + its file pointer positioned at beginning of file. */ + /* FIXME: adding the lseek conjunct is a kludge. + Once there's a reasonable test suite, fix the true culprit: + file_lines. file_lines shouldn't presume that the input + file pointer is initially positioned to beginning of file. */ + if (S_ISREG (stats.st_mode) + && lseek (fd, (off_t) 0, SEEK_CUR) == (off_t) 0) + { + length = lseek (fd, (off_t) 0, SEEK_END); + if (length != 0 && file_lines (filename, fd, n_lines, length)) + return 1; + dump_remainder (filename, fd); + } + else + return pipe_lines (filename, fd, n_lines); + } + return 0; +} + +/* Display the last N_UNITS units of file FILENAME, open for reading + in FD. + Return 0 if successful, 1 if an error occurred. */ + +static int +tail (const char *filename, int fd, off_t n_units) +{ + if (count_lines) + return tail_lines (filename, fd, (long) n_units); + else + return tail_bytes (filename, fd, n_units); +} + +/* Display the last N_UNITS units of file FILENAME. + "-" for FILENAME means the standard input. + FILENUM is this file's index in the list of files the user gave. + Return 0 if successful, 1 if an error occurred. */ + +static int +tail_file (const char *filename, off_t n_units, int filenum) +{ + int fd, errors; + struct stat stats; + + if (!strcmp (filename, "-") + { + have_read_stdin = 1; + filename = "standard input"; + if (print_headers) + write_header (filename, NULL); + errors = tail (filename, 0, n_units); + if (forever_multiple) + { + if (fstat (0, &stats) < 0) + { + error (0, errno, "standard input"); + errors = 1; + } + else if (!S_ISREG (stats.st_mode)) + { + error (0, 0, + "standard input: cannot follow end of non-regular file"); + errors = 1; + } + if (errors) + file_descs[filenum] = -1; + else + { + file_descs[filenum] = 0; + file_sizes[filenum] = stats.st_size; + } + } + } + else + { + /* Not standard input. */ + fd = open (filename, O_RDONLY); + if (fd == -1) + { + if (forever_multiple) + file_descs[filenum] = -1; + error (0, errno, "%s", filename); + errors = 1; + } + else + { + if (print_headers) + write_header (filename, NULL); + errors = tail (filename, fd, n_units); + if (forever_multiple) + { + if (fstat (fd, &stats) < 0) + { + error (0, errno, "%s", filename); + errors = 1; + } + else if (!S_ISREG (stats.st_mode)) + { + error (0, 0, "%s: cannot follow end of non-regular file", + filename); + errors = 1; + } + if (errors) + { + close (fd); + file_descs[filenum] = -1; + } + else + { + file_descs[filenum] = fd; + file_sizes[filenum] = stats.st_size; + } + } + else + { + if (close (fd)) + { + error (0, errno, "%s", filename); + errors = 1; + } + } + } + } + + return errors; +} + +extern int +tai_main (int argc, char **argv) +{ + enum header_mode header_mode = multiple_files; + int exit_status = 0; + /* If from_start, the number of items to skip before printing; otherwise, + the number of items at the end of the file to print. Initially, -1 + means the value has not been set. */ + off_t n_units = -1; + long int tmp_long; + int c; /* Option character. */ + int n_files; + char **file; + + program_name = argv[0]; + have_read_stdin = 0; + count_lines = 1; + forever = forever_multiple = from_start = print_headers = 0; + + if (argc > 1 + && ((argv[1][0] == '-' && ISDIGIT (argv[1][1])) + || (argv[1][0] == '+' && (ISDIGIT (argv[1][1]) + || argv[1][1] == 0)))) + { + /* Old option syntax: a dash or plus, one or more digits (zero digits + are acceptable with a plus), and one or more option letters. */ + if (argv[1][0] == '+') + from_start = 1; + if (argv[1][1] != '\0') + { + strtol_error s_err; + char *p; + + s_err = xstrtol (++argv[1], &p, 0, &tmp_long, "bkm"); + n_units = tmp_long; + if (s_err == LONGINT_OVERFLOW) + { + STRTOL_FATAL_ERROR (argv[1], "argument", s_err); + } + + /* If a [bkm] suffix was given then count bytes, not lines. */ + if (p[-1] == 'b' || p[-1] == 'k' || p[-1] == 'm') + count_lines = 0; + + /* Parse any appended option letters. */ + while (*p) + { + switch (*p) + { + case 'c': + /* Interpret N_UNITS as # of bytes. */ + count_lines = 0; + break; + + case 'f': + forever = 1; + break; + + case 'l': + count_lines = 1; + break; + + case 'q': + header_mode = never; + break; + + case 'v': + header_mode = always; + break; + + default: + error (0, 0, "unrecognized option '%c'", *p); + usage (tail_usage); + } + ++p; + } + } + /* Make the options we just parsed invisible to getopt. */ + argv[1] = argv[0]; + argv++; + argc--; + } + + if (show_version) + { + printf ("tail - %s\n", PACKAGE_VERSION); + exit (EXIT_SUCCESS); + } + + if (show_help) + usage (tail_usage); + + if (n_units == -1) + n_units = DEFAULT_N_LINES; + + /* To start printing with item N_UNITS from the start of the file, skip + N_UNITS - 1 items. `tail +0' is actually meaningless, but for Unix + compatibility it's treated the same as `tail +1'. */ + if (from_start) + { + if (n_units) + --n_units; + } + + n_files = argc - optind; + file = argv + optind; + + if (n_files > 1 && forever) + { + forever_multiple = 1; + forever = 0; + file_descs = (int *) xmalloc (n_files * sizeof (int)); + file_sizes = (off_t *) xmalloc (n_files * sizeof (off_t)); + } + + if (header_mode == always + || (header_mode == multiple_files && n_files > 1)) + print_headers = 1; + + if (n_files == 0) + { + exit_status |= tail_file ("-", n_units, 0); + } + else + { + int i; + for (i = 0; i < n_files; i++) + exit_status |= tail_file (file[i], n_units, i); + + if (forever_multiple) + tail_forever (file, n_files); + } + + if (have_read_stdin && close (0) < 0) + error (EXIT_FAILURE, errno, "-"); + if (fclose (stdout) == EOF) + error (EXIT_FAILURE, errno, "write error"); + exit (exit_status == 0 ? EXIT_SUCCESS : EXIT_FAILURE); +} -- cgit v1.2.3