在bash顶部添加html注释

Question

您好，我必须编写一个简短的程序来接收输入并将其添加到文件的顶部，并在html注释中添加时间戳到文件的底部。只是有点困惑如何做到这一点

echo "What would you like to add to the top of the file 
read x 
cat $x >> File1 

但是，这是在文件的末尾添加这个？提前致谢！

Answer 1

#!/bin/bash 

# No go, if file not existant 
test -f "$1" || exit 1 

# Need a temp filename. Yes, this is racy. 
test -f "$1.tmp" && exit 1 

# Read text 
echo 'What would you like to add to the top of the file?' 
read COMMENT 

# Exit on empty text 
test -z "$COMMENT" && exit 1 

# Write header 
mv "$1" "$1.tmp" 
echo -n "<!-- $COMMENT -->" > "$1" 

# Write content 
cat "$1.tmp" >> "$1" 
rm "$1.tmp" 

# Write footer 
TS=$(date) 
echo -e "\n<!-- $TS -->" >> "$1" 

Answer 2

read -p 'What would you like to add at the top of the file?' header 
cat - "$oldfile" <<< "$header" > "$newfile" 

或

printf '%s\n' 'What would you like to add at the top of the file?' \ 
    '(hit ctrl-c on newline to commit, or ctrl-c to abort.)' 
cat - "$oldfile" > "$newfile" 

Answer 3

这里就是shell的分组构造派上用场：

comment() { echo "<!-- $* -->"; } 
read -p "what?" top 
{ comment "$top"; cat $htmlfile; comment $(date); } > $htmlfile.new 

Answer 4

echo "What would you like to add to the top of the file 
read x 
sed -i '1s/^/$x/' file