Bash字符串比较不eval为true

Question

我有一个脚本,我想找出HTTP请求的状态代码.但是,该if陈述从未评估为真,我不明白为什么.

#!/bin/sh

set -e

CURL='/usr/bin/curl'
CURL_ARGS='-o - -I -s'
GREP='/usr/bin/grep'

url="https://stackoverflow.com"

res=$($CURL $CURL_ARGS $url | $GREP "HTTP/1.1")

echo $res # This outputs 'HTTP/1.1 200 OK'
echo ${#res} # This outputs 16, even though it should be 15

if [ "$res" == "HTTP/1.1 200 OK" ]; then # This never evaluates to true
  echo "It worked"
  exit 1
fi

echo "It did not work"

我检查了res它的长度,它是16,我在浏览器的控制台中检查它是15,所以我通过删除两端的空格来修剪它但仍然没有评估为真.

res_trimmed="$(echo "${res}" | sed -e 's/^[[:space:]]*//' -e 's/[[:space:]]*$//')"

它仍然无法正常工作.

可能有什么不对？任何帮助表示赞赏.谢谢.

Answer 1

更好的实践实现可能如下所示:

#!/usr/bin/env bash
#              ^^^^- ensure that you have bash extensions available, rather than being
#                    only able to safely use POSIX sh syntax. Similarly, be sure to run
#                    "bash yourscript", not "sh yourscript".

set -o pipefail  # cause a pipeline to fail if any component of it fails

url="https://stackoverflow.com"

# curl -f == --fail => tell curl to fail if the server returns a bad (4xx, 5xx) response
res=$(curl -fsSI "$url" | grep "HTTP/1.1") || exit
res=${res%$'\r'}  # remove a trailing carriage return if present on the end of the line

if [ "$res" = "HTTP/1.1 200 OK" ]; then
  echo "It worked" >&2
  exit 0            # default is the exit status of "echo". Might just pass that through?
fi

echo "It did not work" >&2
exit 1