#!/bin/bash
awk 'BEGIN {FS="\\|"; pat["abc"]; pat["ijk"]}
$1 in pat && /:sessionId=/ {print; delete pat[$1]}'
IyEvYmluL2Jhc2gKCmF3ayAnQkVHSU4ge0ZTPSJcXHwiOyBwYXRbImFiYyJdOyBwYXRbImlqayJdfQokMSBpbiBwYXQgJiYgLzpzZXNzaW9uSWQ9LyB7cHJpbnQ7IGRlbGV0ZSBwYXRbJDFdfScK
YWJjfDA3SmFuMjAxNjpzZXNzaW9uSWQ9RjRERgombHQ7Jmx0O3JhbmRvbSBsb2cgbGluZXMmZ3Q7Jmd0OwpkZWZ8MDhKYW4yMDE2OnNlc3Npb25JZD01NDE1CiZsdDsmbHQ7cmFuZG9tIGxvZyBsaW5lcyZndDsmZ3Q7CmFiY3wwOEphbjIwMTY6c2Vzc2lvbklkPUY0REYKJmx0OyZsdDtyYW5kb20gbG9nIGxpbmVzJmd0OyZndDsKeHl6fDA5SmFuMjAxNjpzZXNzaW9uSWQ9RjNEMgombHQ7Jmx0O3JhbmRvbSBsb2cgbGluZXMmZ3Q7Jmd0Owppamt8MDZKYW4yMDE2OnNlc3Npb25JZD1DRjM4
abc|07Jan2016:sessionId=F4DF
<<random log lines>>
def|08Jan2016:sessionId=5415
<<random log lines>>
abc|08Jan2016:sessionId=F4DF
<<random log lines>>
xyz|09Jan2016:sessionId=F3D2
<<random log lines>>
ijk|06Jan2016:sessionId=CF38