suggesting small improvement

[Dimo Bozduganov]

I'm suggesting a small and simple addition to `cut` options.
Sometimes it is very useful to add some text around each line of `cut`
output in a pipeline. Most people use `sed` or something as big as `sed`,
but it would be much better if you can add this text directly in cut
options. Furthermore, `cut` would be suitable for simple concatenating
of strings around any input - for example output from `expr match`.

I suggest these options to be added:

    -A, --output-before=STRING output STRING before each line
    -Z, --output-after=STRING  output STRING after each line

As a source I used `cut.c` from

    ftp://alpha.gnu.org/gnu/coreutils/coreutils-5.3.0.tar.gz

, and I'm supplying the unified diff below.

Here is an example of a pipeline, that I recently used with patched `cut`:

    ls -1|cut -d '.' -f 1 -A 'INSERT INTO mytable(file) VALUES("' -Z '");'

, so the output is SQL, suitable for direct execution. Here is the diff:


--- cut.5.3.0.c 2005-05-07 17:32:35.000000000 +0300
+++ cut.5.3.0.c.patched 2005-05-07 17:49:22.000000000 +0300
@@ -146,6 +146,12 @@
 /* True if we have ever read standard input. */
 static bool have_read_stdin;

+/* The before and after result parts in output. */
+static char *output_before_string;
+static bool output_before_specified;
+static char *output_after_string;
+static bool output_after_specified;
+
 #define HT_RANGE_START_INDEX_INITIAL_CAPACITY 31

 /* The set of range-start indices.  For example, given a range-spec list like
@@ -172,6 +178,8 @@
   {"only-delimited", no_argument, 0, 's'},
   {"output-delimiter", required_argument, 0, OUTPUT_DELIMITER_OPTION},
   {"complement", no_argument, 0, COMPLEMENT_OPTION},
+  {"output-before", required_argument, 0, 'A'},
+  {"output-after", required_argument, 0, 'Z'},
   {GETOPT_HELP_OPTION_DECL},
   {GETOPT_VERSION_OPTION_DECL},
   {0, 0, 0, 0}
@@ -212,6 +220,10 @@
                             or fields.\n\
 "), stdout);
       fputs (_("\
+  -A, --output-before=STRING output STRING before each line\n\
+  -Z, --output-after=STRING  output STRING after each line\n\
+"), stdout);
+      fputs (_("\
   -s, --only-delimited    do not print lines not containing delimiters\n\
       --output-delimiter=STRING  use STRING as the output delimiter\n\
                             the default is to use the input delimiter\n\
@@ -543,6 +555,11 @@

       if (c == '\n')
        {
+               if(output_after_specified) {
+                       fwrite (output_after_string, sizeof (char),
+                               strlen(output_after_string), stdout)
+                       ;
+               }
          putchar ('\n');
          byte_idx = 0;
          print_delimiter = false;
@@ -557,6 +574,13 @@
        {
          bool range_start;
          bool *rs = output_delimiter_specified ? &range_start : NULL;
+               if(byte_idx==0) {
+                       if(output_before_specified) {
+                               fwrite (output_before_string, sizeof (char),
+                                       strlen(output_before_string), stdout)
+                               ;
+                       }
+               }
          if (print_kth (++byte_idx, rs))
            {
              if (rs && *rs && print_delimiter)
@@ -580,6 +604,7 @@
   size_t field_idx = 1;
   bool found_any_selected_field = false;
   bool buffer_first_field;
+  bool output_before = false;

   c = getc (stream);
   if (c == EOF)
@@ -626,9 +651,24 @@
                }
              else
                {
+                       if(output_before_specified) {
+                               fwrite (output_before_string, sizeof (char),
+                                       strlen(output_before_string), stdout)
+                               ;
+                               output_before=true;
+                       }
+      if (field_1_buffer[n_bytes - 1] != '\n')
                  fwrite (field_1_buffer, sizeof (char), n_bytes, stdout);
+                       else
+                         fwrite (field_1_buffer, sizeof (char), n_bytes-1, 
stdout)
+                       ;
+                       if(output_after_specified) {
+                               fwrite (output_after_string, sizeof (char),
+                                       strlen(output_after_string), stdout)
+                               ;
+                       }
                  /* Make sure the output line is newline terminated.  */
-                 if (field_1_buffer[n_bytes - 1] != '\n')
+      /* if (field_1_buffer[n_bytes - 1] != '\n') */ /* newline removed anyway 
*/
                    putchar ('\n');
                }
              continue;
@@ -636,6 +676,12 @@
          if (print_kth (1, NULL))
            {
              /* Print the field, but not the trailing delimiter.  */
+                               if(output_before_specified) {
+                                       fwrite (output_before_string, sizeof 
(char),
+                                               strlen(output_before_string), 
stdout)
+                                       ;
+                                       output_before=true;
+                               }
              fwrite (field_1_buffer, sizeof (char), n_bytes - 1, stdout);
              found_any_selected_field = true;
            }
@@ -644,6 +690,15 @@

       if (c != EOF)
        {
+    if (found_any_selected_field
+        || !(suppress_non_delimited && field_idx == 1)) {
+                                       
if(output_before_specified&&(!output_before)) {
+                                               fwrite (output_before_string, 
sizeof (char),
+                                                       
strlen(output_before_string), stdout)
+                                               ;
+                                               output_before=true;
+                                       }
+               }
          if (print_kth (field_idx, NULL))
            {
              if (found_any_selected_field)
@@ -682,8 +737,15 @@
       else if (c == '\n' || c == EOF)
        {
          if (found_any_selected_field
-             || !(suppress_non_delimited && field_idx == 1))
+        || !(suppress_non_delimited && field_idx == 1)) {
+                       if(output_after_specified) {
+                               fwrite (output_after_string, sizeof (char),
+                                       strlen(output_after_string), stdout)
+                               ;
+                       }
+                       output_before=false;
            putchar ('\n');
+               }
          if (c == EOF)
            break;
          field_idx = 1;
@@ -765,7 +827,7 @@
   delim = '\0';
   have_read_stdin = false;

-  while ((optc = getopt_long (argc, argv, "b:c:d:f:ns", longopts, NULL)) != -1)
+  while ((optc = getopt_long (argc, argv, "A:Z:b:c:d:f:ns", longopts, NULL)) 
!= -1)
     {
       switch (optc)
        {
@@ -785,7 +847,19 @@
          operating_mode = field_mode;
          spec_list_string = optarg;
          break;
-
+               
+  case 'A':
+    /* output this before the result */
+    output_before_string = xstrdup (optarg);
+               output_before_specified=true;
+    break;
+               
+  case 'Z':
+    /* output this after the result */
+    output_after_string = xstrdup (optarg);
+               output_after_specified=true;
+    break;
+               
        case 'd':
          /* New delimiter. */
          /* Interpret -d '' to mean `use the NUL byte as the delimiter.'  */


--
Dimo Bozduganov
DVR Review