linux – 读取bash环境变量

TIME=1328189073
CLIENT[if-modified-since]=Thu,02 Feb 2012 12:09:40 GMT
HTTP_FILE=/news/rss.xml?edition=uk
HTTP_PORT=80
HTTP_HOST=feeds.bbci.co.uk
HTTP_PROTO=http
CLIENT[host]=feeds.bbci.co.uk
CLIENTID=10
CLIENT[user-agent]=Safari
PWD=/
VERSION=SR.4.2.2.MR.20110523
CLIENT[accept]=text/html,application/xhtml+xml,application/xml;q=0.9,*/*;q=0.8
SHLVL=1
CLIENT[accept-language]=en-gb,en;q=0.5
INTERFACE=192.168.221.196
CLIENT[cache-control]=max-age=0
CLIENT[accept-encoding]=gzip,deflate
HTTP_METHOD=GET
CLIENT[user-agent]

但是,当我尝试从bash脚本访问此变量之一时,它没有给出任何结果

echo ${CLIENT[user-agent]} >> ${LOG}

但这很有效

echo ${TIME} ${CLIENTID} ${USERNAME} ${IP} ${HTTP_METHOD} ${HTTP_PROTO} ${HTTP_HOST} ${HTTP_PORT} ${HTTP_FILE} ${SIZE} >> ${LOG}

知道用户代理无法显示的原因吗？