Useful Linux Command for Oracle DBA

--Create new tar

#tar -cvf tar_file_name.tar dirname/

--Extract from tar

#tar -xvf tar_file.tar

--view tar file

#tar -tvf tar_file_name.tar

--Search for given string

#grep -i "hostname" file_name

--Search for a given string in all files recursively

#grep -r "hostname" *

--Find file

#find -iname "filename"

--Execute commands on files found by the find command

#find -iname "filename" -exec rm -rf {} \;  --It will find the file and delete it.

--Find empty files in home directory



#find ~ -empty

--Convert DOS file to Unix file format

#sed 's/.$//' filename

--Print file content in reverse order

#sed -n     '1!G;h;$p' filename

--Add line number for all non-empty-lines in a file

#sed '/./=' filename | sed 'N; s/\n/ /'

--Remove duplicate lines using awk

#awk '!($0 in array) { array[$0]; print }' filename

--Print all lines from /etc/passwd that has the same uid and gid

#awk -F ':' '$3==$4' passwd.txt

--Print only specific field from a file.

#awk '{print $2,$5;}' filename

--Sort a file in ascending order

#sort filename

--Sort a file in descending order

#sort -r filename

--Sort passwd file by 3rd field.

#sort -t: -k 3n /etc/passwd | more

--To view oracle related environment variables.

$export |grep ORACLE

--Visual Classification of Files With Special Characters Using ls -F

#ls -F

--To create a *.gz compressed file:

#gzip filename

--To uncompress a *.gz file:

#gzip -d filename.gz

--Display compression ratio of the compressed file using gzip -l

#gzip -l *.gz

--To create a *.bz2 compressed file:

#bzip2 filename

--To uncompress a *.bz2 file:

#bzip2 -d filename.bz2

--To extract a *.zip compressed file:

#unzip filename.zip

--View the contents of *.zip file without unzipping it:

#unzip -l filename.zip

---Shutdown the system and turn the power off immediately.

#shutdown -h now

---Shutdown the system after 10 minutes.

#shutdown -h +10

---Reboot the system using shutdown command.

#shutdown -r now

---Force the filesystem check during reboot.

#shutdown -Fr now

---Give full access to user and group (i.e read, write and execute ) on a specific file.

#chmod ug+rwx filename

---Revoke all access for the group (i.e read, write and execute ) on a specific file.

#chmod g-rwx filename

--Syncronize hardware clock after changing the system time

#hwclock –systohc