regex101: PCRE (Legacy) Substitution Workspace

Regular Expression

(?m)^(.*)JSESSIONID=.*((?=\"\s\").*)$

New

189.222.1.46 - - [24/Jul/2014:11:27:00] "GET /flower_store/product.screen?product_id=RP-SN-01 HTTP/1.1" 200 10897 "http://mystore.splunk.com/flower_store/category.screen?category_id=BALLOONS&JSESSIONID=SD1SL10FF3ADFF3" "Mozilla/5.0 (X11; U; Linux i686; en-US; rv:1.8.0.10) Gecko/20070223 CentOS/1.5.0.10-0.1.el4.centos Firefox/1.5.0.10" 527 3006
10.2.91.38 - - [24/Jul/2014:11:28:00] "POST /flower_store/j_signon_check HTTP/1.1" 302 309
"http://mystore.splunk.com/flower_store/enter_order_information.screen&JSESSIONID=SD1SL10FF3ADFF3" "Mozilla/5.0 (X11; U; Linux i686; en-US; rv:1.8.0.10) Gecko/20070223 CentOS/1.5.0.10-0.1.el4.centos Firefox/1.5.0.10" 3441 2576
192.0.1.38 - - [24/Jul/2014:11:28:15] "GET /flower_store/images/cat3.gif HTTP/1.1" 200 5024 "http://mystore.splunk.com/flower_store/item.screen?item_id=EST-21&JSESSIONID=SD1SL10FF3ADFF3" "Mozilla/5.0 (X11; U; Linux i686; en-US; rv:1.8.0.10) Gecko/20070223 CentOS/1.5.0.10-0.1.el4.centos Firefox/1.5.0.10" 4323 3071

Substitution

$1JSESSIONID=#######$2