07132022.md

1. Comparison between DOS and Linux/UNIX:

Link: How to create Markdown Table

DOS	Linux/UNIX
cd	cd
attrib	chmod
comp	diff
copy	cp
del	rm
rd	rmdir
dir	ls
set	printenv
find	grep
help	man
md	mkdir
move	mv
ren (rename)	mv
date, time	date
chkdsk	df
type	cat
type <filename> | more	more
sort	sort

• Example:

dir | sort /R

2. Some grep examples integrated with find and globstar: **:

• NOTE:

  • glob ~ *: was called as GLOB expression.
  • If Bash version is 4 or higher, can make use of Bash’s globstar (**) to match files recursively.

• exp1: Using grep with --include=Glob, search for the pattern only with the .log/.md extension recursively in the test/ folder:

grep -R --include=*.log 'Exception' test/
grep -R --include=*.{log,md} 'Exception' test/

• exp2: With globstar expression, the -R recursive option is now totally useless:

grep 'Exception' test/**/*.log
grep 'Exception' test/**/*.{log,md}

• exp3: Only using find command with the example filename pattern "app_20200301.log":

find test/ -type f -a -regextype 'egrep' -regex '.*_[0-9]{8}.*'

• exp4: Combining the find with grep in one command with the -exec action:

find test/ -type f -a -regextype 'egrep' -regex '.*_[0-9]{8}.*' -exec grep -H "Exception" '{}' \;

• NOTE (exp4):

  • The command requires the ending \;. This is because it indicates the termination of the grep command.
  • The -exec action will be executed on each file the find command has found.

• exp5: Using xargs to combine find and grep:

find test/ -type f -a -regextype 'egrep' -regex '.*_[0-9]{8}.*' | xargs grep "Exception"

• NOTE (exp5):

  • xargs will build matched files into bundles and run them through the command as few times as possible.