foo (A1) lsb@lsb-t61-mint ~ $ grep ‘\s’ testgrep-tabs.txt Tue Dec 30 02:25:25 2014 Regular Expressions in grep grep '^$' filename For example, try to math words such as vivek1, Vivek2 and so on: Sample outputs: Let us find all filenames starting with purchase: 3. it should end with following punctuations: .,!? -E. For the purpose of this guide, we'll use the following excerpt (referred to as excerpt.txt) from President Obama's Jan. 10, 2015, weekly address, "Resurgence is Real". Tue Dec 30 02:25:25 2014, i want result as: AQPC started with pid=54, OS id=15112 ^3[47]\d{13}$