cat: split POSIX, BSD and GNU and add 2 examples (#9623)

Co-authored-by: Emily Grace Seville <EmilySeville7cfg@gmail.com>

pages/common/cat.md

@@ -9,16 +9,16 @@
 
 - Concatenate several files into an output file:
 
-`cat {{path/to/file1}} {{path/to/file2}} > {{path/to/output_file}}`
+`cat {{path/to/file1 path/to/file2 ...}} > {{path/to/output_file}}`
 
-- Append several files into an output file:
+- Append several files to an output file:
 
-`cat {{path/to/file1}} {{path/to/file2}} >> {{path/to/output_file}}`
+`cat {{path/to/file1 path/to/file2 ...}} >> {{path/to/output_file}}`
 
-- Number all output lines:
+- Copy the contents of a file into an output file without buffering:
 
-`cat -n {{path/to/file}}`
+`cat -u {{/dev/tty12}} > {{/dev/tty13}}`
 
-- Display non-printable and whitespace characters (with `M-` prefix if non-ASCII):
+- Write `stdin` to a file:
 
-`cat -v -t -e {{path/to/file}}`
+`cat - > {{path/to/file}}`

pages/linux/cat.md

@@ -0,0 +1,32 @@
+# cat
+
+> Print and concatenate files.
+> More information: <https://www.gnu.org/software/coreutils/cat>.
+
+- Print the contents of a file to the standard output:
+
+`cat {{path/to/file}}`
+
+- Concatenate several files into an output file:
+
+`cat {{path/to/file1 path/to/file2 ...}} > {{path/to/output_file}}`
+
+- Append several files to an output file:
+
+`cat {{path/to/file1 path/to/file2 ...}} >> {{path/to/output_file}}`
+
+- Copy the contents of a file into an output file in [u]nbuffered mode:
+
+`cat -u {{/dev/tty12}} > {{/dev/tty13}}`
+
+- Write `stdin` to a file:
+
+`cat - > {{path/to/file}}`
+
+- [n]umber all output lines:
+
+`cat -n {{path/to/file}}`
+
+- Display non-printable and whitespace characters (with `M-` prefix if non-ASCII):
+
+`cat -v -t -e {{path/to/file}}`

pages/osx/cat.md

@@ -0,0 +1,32 @@
+# cat
+
+> Print and concatenate files.
+> More information: <https://keith.github.io/xcode-man-pages/cat.1.html>.
+
+- Print the contents of a file to the standard output:
+
+`cat {{path/to/file}}`
+
+- Concatenate several files into an output file:
+
+`cat {{path/to/file1 path/to/file2 ...}} > {{path/to/output_file}}`
+
+- Append several files to an output file:
+
+`cat {{path/to/file1 path/to/file2 ...}} >> {{path/to/output_file}}`
+
+- Copy the contents of a file into an output file without buffering:
+
+`cat -u {{/dev/tty12}} > {{/dev/tty13}}`
+
+- Write `stdin` to a file:
+
+`cat - > {{path/to/file}}`
+
+- Number all output lines:
+
+`cat -n {{path/to/file}}`
+
+- Display non-printable and whitespace characters (with `M-` prefix if non-ASCII):
+
+`cat -v -t -e {{path/to/file}}`