Zipping Files

Command	Options	Description
1. gzip	gzip etl_code eg:etl_code.gz
	gunzip etl_code.gz eg: etl_code
	zip file*sql eg: file.zip
	unzip file.zip eg:file*sql
2. tar		create backup of files recursively.
	-cvf eg :tar -cvf /home/gagan/sqlbackup ./*.sql
	- x eg:tar-xcvf /home/gagan/sqlbackup ./*.sql	files are restored using -x option.
3. Cut	-c <column start and no> eg : cut -c -5,6-12 test file	column (by specifying position). C stands for column cut.
	-f <field start and end no> eg:cut -f 1,5 test file	field (default deliminator tab). F stands for field cut.
	'-d -f <field start and end no> eg: cut -d "|" -f 1,5 test file | new file	Cut the field b/w 1 and 5 and piped the output to new file.
4. sort	sort test file	By default the sorting starts with first character of each line. Priority1.space, tabs 2. numerals 3.uppercase letters 4. Lower case letters.
	-t eg : sort -t "|" +2 test file	Sorting starts from 3rd field skipping 2nd field, overring the default.delimiter to distinguish b/w start and end of field.
	-r eg : sort -t \| -r +2 test file	Reverse sort starting with 3rd field.
	eg : sort -t \|  +2r test file	The above command can be written in another way.
	-o eg : sort -o abc.txt abc_sort.txt	save sorted data in file.
	eg : sort -t "|" +1 -2 +3 <>	Sorting based on different field as in case of order by clause.Sorting starts with 2nd field then with 4th field, -2 indicate to stop the sorting after 2nd field and resume it with 3rd field.
	-n eg : sort -n <>	Numeric sort.
	-u eg : sort -u <>	Unique sort.
5.paste	-d eg:paste -d "|" <> <>	deliminator.
6.tr	eg : tr '|\' '~-' <test.txt	translate all | with ~ and \ with - .
	eg : tr '[a-z]' '[A-Z] <test.txt	translate to upper case.
	-d eg : tr -d '|' test.txt	delete all occurrence of | .
7.uniq		Unique require sorted file as input.
	-u eg : cut -d "|" -f3 <>|sort|uniq -u	remove duplicate.
	-d eg: cut -d "|" -f3 <>|sort|uniq -d	select only dup records.
	-c eg : cut -d "|" -f3|sort|uniq -c	duplicate  count.
8.Changing time stamp		touch mon date hrs mins <file>.
ls -lt	time of last modification	touch -m 01290430 <file>.
ls -lu	time of last access	touch -a 01290415 <file>.
9.Change Date	date 09181754
10.wall	wall -g dba "hello"	to selectively send msg to dba group.
11.shutdown	shutdown -g2	power down after 2 mins.
	shutdown -y -g0	immediate shutdown.
	shutdown -y -g0 -i6	shutdown and reboot (init level 6).
	shutdown 17:30	shutdown at 17:30.
	shutdown -r now	shutdown immediate and reboot.
12. du		Disk usage.
	du /home/expimp/create_db	tree output for each directory inside.
	du -s //home/expimp/create_db	summary.
13.find	find <loc> <option> <pattern> <action>	find in root dir abc in emp.lst file
	'-mtime = mod time eg: find . -mtime -2 -print	find file modi in less then 2 days.
	'atime = access time eg: find . -atime +365 -print	find the file not accessed in last 1 year.
	! –newer eg: find / -name "*.pl" ! -newer last_backup -print	file modi before last_backup.
	-size. eg: find . -size +2048 -print	files greater then x blocks.
	-a (and) -o (OR) eg: find . \( -name "*.sh" -o -name "*.lst" \) -print	double quotes necessary.
	-exec eg: find . -atime +180 -ok rm -f {} \;	remove the files which are not modi for last 20 days
	-ok eg: find . -atime +180 -ok rm -f {} \;	before removing prompt for confirmation.
	xargs eg: find . -mtime +20 | xargs rm -f	remove all file rm will be executed only once.
	xargs -n -p –t eg:find . -mtime +20 | xargs -n20 -p -t rm -f	remove at max 20 files in batch and in interactive mode.
	-type eg: find / -name log -type f -print	f for file and d for directory.
	-prune eg: find . -name *.log -prune exe –print.	don't descend exe directory.