Hello! I sometimes use 'cat -E' as a quick check for lines with trailing
white space. I understand that '$' was chosen as the end-of-line character
due to its usage in regular expressions. However, I like to use a more
conspicuous character, such as '@'. So, I thought, how about letting the
user specify the end-of-line character? While doable with 'sed', it was
quite easy to add an option to accomplish this. My proposed new syntax is:
cat -E -c @ ...
or
cat --show-ends --end-char=@ ...
It is minimally intrusive and does not affect backward compatibility: when
one of the new options is not specified, the end-of-line character is still
'$'. Alternatively, use of one of these options could automatically turn-on
displaying an end-of-line character
(just add "show_ends = true;" within the new case).
Here's my patch submitted for your perusal. It is applied to
coreutils-8.20, the current latest stable release. If you decide to include
it, feel free to make any changes you see fit. Thanks!
-- Tom
diff -ru coreutils-8.20/doc/coreutils.texi coreutils-new/doc/coreutils.texi
--- coreutils-8.20/doc/coreutils.texi 2012-10-23 10:14:12.000000000 -0400
+++ coreutils-new/doc/coreutils.texi 2013-02-09 21:35:23.000000000 -0500
@@ -1509,6 +1509,12 @@
@opindex --number-nonblank
Number all nonempty output lines, starting with 1.
+@item -c
+@itemx --end-char=CHAR
+@opindex -c
+@opindex --end-char=CHAR
+With @option{-E}, use CHAR for the end of line character.
+
@item -e
@opindex -e
Equivalent to @option{-vE}.
@@ -1517,7 +1523,7 @@
@itemx --show-ends
@opindex -E
@opindex --show-ends
-Display a @samp{$} after the end of each line.
+Display a character (default @samp{$}) after the end of each line.
@item -n
@itemx --number
diff -ru coreutils-8.20/src/cat.c coreutils-new/src/cat.c
--- coreutils-8.20/src/cat.c 2012-10-23 10:14:12.000000000 -0400
+++ coreutils-new/src/cat.c 2013-02-09 21:48:13.000000000 -0500
@@ -94,8 +94,9 @@
\n\
-A, --show-all equivalent to -vET\n\
-b, --number-nonblank number nonempty output lines, overrides -n\n\
+ -c, --end-char=CHAR with -E, use CHAR for the end of line character\n\
-e equivalent to -vE\n\
- -E, --show-ends display $ at end of each line\n\
+ -E, --show-ends display a character (default $) at end of each line\n\
-n, --number number all output lines\n\
-s, --squeeze-blank suppress repeated empty output lines\n\
"), stdout);
@@ -231,7 +232,8 @@
bool number,
bool number_nonblank,
bool show_ends,
- bool squeeze_blank)
+ bool squeeze_blank,
+ char end_char)
{
/* Last character read from the input buffer. */
unsigned char ch;
@@ -395,10 +397,11 @@
}
}
- /* Output a currency symbol if requested (-e). */
+ /* Output an end of line character (default currency symbol)
+ if requested (-E). */
if (show_ends)
- *bpout++ = '$';
+ *bpout++ = end_char;
/* Output the newline. */
@@ -543,10 +546,12 @@
bool show_nonprinting = false;
bool show_tabs = false;
int file_open_mode = O_RDONLY;
+ char end_char = '$';
static struct option const long_options[] =
{
{"number-nonblank", no_argument, NULL, 'b'},
+ {"end-char", required_argument, NULL, 'c'},
{"number", no_argument, NULL, 'n'},
{"squeeze-blank", no_argument, NULL, 's'},
{"show-nonprinting", no_argument, NULL, 'v'},
@@ -572,7 +577,7 @@
/* Parse command line options. */
- while ((c = getopt_long (argc, argv, "benstuvAET", long_options, NULL))
+ while ((c = getopt_long (argc, argv, "bc:enstuvAET", long_options, NULL))
!= -1)
{
switch (c)
@@ -582,6 +587,13 @@
number_nonblank = true;
break;
+ case 'c':
+ if (optarg[0] == '\0' || optarg[1] != '\0')
+ error (EXIT_FAILURE, 0,
+ "only one character is allowed at the end of each line");
+ end_char = optarg[0];
+ break;
+
case 'e':
show_ends = true;
show_nonprinting = true;
@@ -761,7 +773,7 @@
ok &= cat (ptr_align (inbuf, page_size), insize,
ptr_align (outbuf, page_size), outsize, show_nonprinting,
show_tabs, number, number_nonblank, show_ends,
- squeeze_blank);
+ squeeze_blank, end_char);
free (outbuf);
}
diff -ru coreutils-8.20/tests/misc/cat-proc.sh coreutils-new/tests/misc/cat-proc.sh
--- coreutils-8.20/tests/misc/cat-proc.sh 2012-10-23 10:14:12.000000000 -0400
+++ coreutils-new/tests/misc/cat-proc.sh 2013-02-08 19:31:07.000000000 -0500
@@ -1,5 +1,6 @@
#!/bin/sh
-# Ensure that cat -E produces same output as cat, module '$'s,
+# Ensure that cat -E and cat -E -c @ produce same output
+# as cat, module '$'s and '@'s, respectively,
# even when applied to a file in /proc.
# Copyright (C) 2006-2012 Free Software Foundation, Inc.
@@ -30,9 +31,11 @@
# If that happens, consider choosing a file that's less likely to change,
# or just filter out the changing lines. The sed filter should help
# to avoid any spurious numeric differences.
-cat -E $f | sed 's/[0-9][0-9]*/D/g' | tr -d '$' > out || fail=1
-cat $f | sed 's/[0-9][0-9]*/D/g' | tr -d '$' > exp || fail=1
+cat -E $f | sed 's/[0-9][0-9]*/D/g' | tr -d '$' > out1 || fail=1
+cat -E -c @ $f | sed 's/[0-9][0-9]*/D/g' | tr -d '@' > out2 || fail=1
+cat $f | sed 's/[0-9][0-9]*/D/g' | tr -d '$' > exp || fail=1
-compare exp out || fail=1
+compare exp out1 || fail=1
+compare exp out2 || fail=1
Exit $fail
