Syed Saad Ali

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Syed Saad Ali

Oracle ACE Pro

Oracle Solution Architect

Oracle E-Business Suite

Oracle Cloud Infrastructure

Oracle Fusion Middleware

Oracle Database Administration

Oracle Weblogic Administration

Blog Post

Useful Commands For Unix Operating System

Useful Commands For Unix Operating System

Useful Commands For Unix Operating System

 

1.Deleting files older than N number of days ?

find . -name ‘*.trc’ -mtime +[N in days]  -exec rm {} \;  
Command will delete files older then N days in that directory

 

2.Copying file keeping timestamp preserve

cp -ip file.txt file_txt_bkp

 

3.Listing files modified in last N days

find . -mtime -<ndays> -exec ls -lt {} \;

 

4.Sorting files based on Size of file ? 

ls -l | sort -nrk 5  | more
du -sm *|sort -nr|head -10 

 

5.Finding CPU & Memory detail 

->cat /proc/cpuinfo  (CPU)
->cat /proc/meminfo (Memory)
->topas

 

6.Finding if any service is listening on particular port or not ?

netstat -an | grep {port no}  

 

7.Finding Process ID (PID) associated with any port ?

lsof | grep {port no.}  
lsof should be installed and in path.Many times it will be installed eith root user.Make sure you have that permission

 

9.Finding a pattern in some file in a directory ?

grep pattern  file_name  ( find pattern in particular file )
grep -i pattern  file_name (find pattern ignoring the case)

 

10.Create symbolic link to a file ?

ln -s  pointing_to_original_file  symbolic_link_name

example
 ln -s /home/text.txt test.txt

 

11.History of command executed in UNIX 

fc -l 
fc -e – ls ( Would execute the last ls command.) 
History command will also do the same
history

 

12. Compressing a big file

zip -r new.zip new
or
compress file_name

 

13.Creating a tar file

tar -cvwf file.tar file.txt

 

14.Extracting the files from a tar file

tar -xvwf myfile.tar(System would unarchive (untar) the myfile.tar file into the current directory.)
tar -xvwzf myfile.tar.gz(System would unarchive (untar) the myfile.tar.gz file in the current directory.)

 

14.Extracting a gz file?

Use guzip command as follows:
gunzip file.gz
OR
gzip -d file.gz

 

15.Extract a tar.gz or .tgz file?

Files with extension tar.gz or .tgz are tar files compressed with gzip. On Unix system extract them with following command:
gunzip < file.tar.gz | tar xvf –
gunzip < file.tgz | tar xvf –

If you have GNU tar (Linux system) you can use the z option directly:
tar xvzf file.tar.gz
tar xvzf file.tgz

 

16.Using mailx command

echo “This is going to be body of the mail” |mailx -s “Subject:Testing” “false@gmail.com”

 

17.Checking the file system free and used space

df -gt 

 

 

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