第四章：Tweaking Unix--32.額外顯示文件信息

   爲了讓用戶更加便捷的瞭解到文件的內容，從而對用戶提供幫助，該腳本的目的就是能夠在顯示文件自己內容的基礎上，再多概括總結幾行。

#!/bin/sh

# showfile.sh -- 展現一個文件的內容, 也包括有用的額外信息

width=72

for input
do
	lines="$(wc -l < $input | sed 's/ //g')"
	chars="$(wc -c < $input | sed 's/ //g')"
	owner="$(ls -ld $input | awk '{print $3}')"
	echo "----------------------------------------------------------"
	echo "File $input($lines lines, $chars characters, owned by $owner):"
	echo "----------------------------------------------------------"
	while read line
	do
		if [ ${#line} -gt "$width" ]; then
			echo "$line" | fmt.sh | sed -e '1s/^/ /' -e '2,$s/^/+ /'
		else
			echo "$line"
		fi
	done < $input
	echo "----------------------------------------------------------"
done | more

exit 0

這個腳本的功能，你們應該看到了，多出了一些形象化的說明，統計了行數和字符數。在顯示每行的內容時，最多顯示72個字符，假若多於72個，那麼就截斷爲多行。這個腳本中最難的地方就在截斷顯示這兒：

echo "$line" | fmt.sh | sed -e '1s/^/ /' -e '2,$s/^/+ /'

它調用了第14個腳本fmt.sh，用來格式化輸出用，最後一個管道的做用是: 
第一個sed表達式是把傳過來的第一行的首字母處加上一個空格；
第二個sed表達式是把第2行到最後一行的每行的首字母處都添加上一個加號和一個空格；

測試下這個腳本：

$ showfile ragged.txt 
----------------------------------------------------------------- 
 File ragged.txt (7 lines, 639 characters, owned by taylor): 
----------------------------------------------------------------- 
   So she sat on, with closed eyes, and half believed herself in 
   Wonderland, though she knew she had but to open them again, and 
   all would change to dull reality--the grass would be only rustling 
 + in the wind, and the pool rippling to the waving of the reeds--the 
   rattling teacups would change to tinkling sheep-bells, and the 
   Queen's shrill cries to the voice of the shepherd boy--and the 
   sneeze 
   of the baby, the shriek of the Gryphon, and all the other queer 
 + noises, would change (she knew) to the confused clamour of the busy 
 + farm-yard--while the lowing of the cattle in the distance would 
 + take the place of the Mock Turtle's heavy sobs. 
-----------------------------------------------------------------