在/ bin / bash中使用的printf

Question

I use printf in /bin/bash (OS X standard GNU bash, version 3.2.57(1)-release (x86_64-apple-darwin15) Copyright (C) 2007 Free Software Foundation, Inc.

#!/bin/bash
latest_version=\
$((curl -s http://java.com/en/download/installed8.jsp 2>/dev/null || wget -q -O - http://java.com/en/download/installed8.jsp) | grep 'latest8' |sed -E "s/.*= //" |tr -d "';")
echo $latest_version
printf "%s \n" $latest_version

I want to get a string "1.8.0_102" (as of 2016/7/24)

This shows

#echo
1.8.0_101
#printf
8.0_101

I want to make the string in red and the script will be run in both OS X and linux, so I do not want to use echo.

Why can't I get 1.8.0_101 by printf?

Further more what is wrong with this below?

printf "Get the latest Java \033[1;31m %s \033[m from Oracle.\n" $latest_version

It also does not work...

I have a hint... when I put

latest_version=1.8.0_101

then it works.

so the variable input to latest_version by $() is working wrong?

Answer 1

You can pipe your curl with awk to parse latest version:

latest_version=$(curl -s http://java.com/en/download/installed8.jsp |
awk -F= '/latest8/{gsub(/^[^[:digit:]]*|\x27.*$/, "", $2); print $2}')

Answer 2

If you execute:

printf "%q \n" $latest_version

you get:

$'1.8.0_101\r' 

and you can see the redundant \\r (carriage returns) character.

To fix this add the \\r to your tr command and that will work like a charm:

latest_version=$((curl -s http://java.com/en/download/installed8.jsp 2>/dev/null || wget -q -O - http://java.com/en/download/installed8.jsp) | grep 'latest8' |sed -E "s/.*= //" |tr -d "';\r")
printf "%s \n" $latest_version

outputs:

1.8.0_101