use cat instead of self implementation

colines

@@ -10,6 +10,9 @@
 # @online-doc https://github.com/oldratlee/useful-scripts/blob/master/docs/shell.md#beer-colines
 # @author Jerry Lee (oldratlee at gmail dot com)
 
+set -e
+set -o pipefail
+
 # NOTE: $'foo' is the escape sequence syntax of bash
 readonly ec=$'\033' # escape char
 readonly eend=$'\033[0m' # escape end
@@ -23,22 +26,7 @@ colorEcho() {
     [ -t 1 ] && echo "$ec[1;${color}m$@$eend" || echo "$@"
 }
 
-readonly seperator="================================================================================"
-
-if [ $# -eq 0 ]; then
-    # Bash read line does not read leading spaces https://stackoverflow.com/questions/29689172
-    while IFS= read -r line; do
-        colorEcho "$line"
-    done
-else
-    for a; do
-        [ $# -gt 1 ] && {
-            echo "$seperator"
-            echo "$a"
-            echo "$seperator"
-        }
-        while IFS= read -r line; do
-            colorEcho "$line"
-        done < "$a"
-    done
-fi
+# Bash read line does not read leading spaces https://stackoverflow.com/questions/29689172
+cat "$@" | while IFS= read -r line; do
+    colorEcho "$line"
+done

docs/shell.md

@@ -83,8 +83,9 @@ ssh-rsa AAAAB3NzaC1yc2EAAAABIwAAAQEAz+ETZEgoLeIiC0rjWewdDs0sbo8c...== [email protected]
 :beer: [colines](../colines)
 ----------------------
 
-彩色`cat`出文件行，方便人眼区分不同的行。  
-支持`Linux`、`Mac`、`Windows`（`cygwin`、`MSSYS`）。
+彩色`cat`出文件行，方便人眼区分不同的行。
+支持`Linux`、`Mac`、`Windows`（`cygwin`、`MSSYS`）。  
+命令支持选项、功能和使用方式与[`cat`命令](https://linux.die.net/man/1/cat)完全一样（实际上在实现上全部代码给`cat`命令）。
 
 命令名`colines`意思是`COLorful LINES`。
 
@@ -100,15 +101,9 @@ $ echo -e 'a\nb' | nl | colines
 1   a
 2   b
 $ colines file1 file2.txt
-================================================================================
-file1
-================================================================================
 line1 of file1
 line2 of file1
 ...
-================================================================================
-file2.txt
-================================================================================
 line1 of file2
 line2 of file2
 ...