Since the most used operating system for a progress database product is linux/unix/solaris as compared to windows OS, a Progress DBA is expected to have some basic knowledge of unix commands which would be helpful for the dba to troubleshoot daily basis issues.
Here i am providing basic unix commands most of them would only count as pre school lessons for any unix/linux user , later will move on to some helpful commands/utlilities.
File commands:
These would be readily required by a dba, since apart from working on the progress database utility, to operate on the files in form of dumps , structure files, definition files etc a dba would be required to use these commands
1. ls :Directory listing
2. ls -al :Formatted listing with hidden files
3. ls -lt: Sorting the Formatted listing by time modification
4. cd dir :Change directory to dir
5. cd :Change to home directory
6. pwd :Show current working directory
7. mkdir:dir Creating a directory dir
8. cat >file: Places the standard input into the file
9. more file :Output the contents of the file
10. head file :Output the first 10 lines of the file
11. tail file: Output the last 10 lines of the file
12. tail -f file :Output the contents of file as it grows,starting with
the last 10 lines
13. touch file: Create or update file
14. rm file: Deleting the file
15. rm -r dir :Deleting the directory
16. rm -f file :Force to remove the file
17. rm -rf dir: Force to remove the directory dir
18. cp file1 file2 :Copy the contents of file1 to file2
19. cp -r dir1 dir2 :Copy dir1 to dir2;create dir2 if not present
20. mv file1 file2: Rename or move file1 to file2,if file2 is an existing
directory
21. ln -s file :link Create symbolic link link to file
Process Management:
Each progress service including the instance of database runs as a process with a process id on the unix/linux OS systems.To have a track on the process and to perform various operation on the same a dba must be acquinted with process management commands.Having the right command at the right moment during a state of incidents could result in saving a lot of time and effort for the dba.
There can be cases when a progress batch process due to programatical mistakes may go on to perform a infinite loop on the database eating up the memory and space assigned to database.
The commands for processes can be a good tool for such instances.
1. ps: To display the currently working processes
2. top :Display all running process
3. kill pid :Kill the process with given pid
4. killall proc: Kill all the process named proc
5. pkill pattern :Will kill all processes matching the pattern
6. bg :List stopped or background jobs,resume a stopped
job in the background
7. fg :Brings the most recent job to foreground
8. fg n: Brings job n to the foreground
Kill command(3.kill pid) is a very powerful unix command and could be both a savior and a trouble maker at different occasions.The use of kill command should be a judicious decision since the process we are killing might cause more damage after getting killed/evicted than it was causing running.
The kill command syntax goes as
kill [ -s signal] pid
The signal provided would determine the intensity with which the kill command is executed
kill -l would list all the signals which we can use with kill command.Below are various kill signals we can use as per the requirement.It is recommended not to use kill -9 for a db process though,since it is a force kill and may result in damage to the database entities.
NumberSignal NameDescription0SIGNULLUsed to check access to the process id1SIGHUPHup signal. Terminates the process.2SIGNINTInterrupt signal. Terminating the process3SIGQUITQuit signal. Terminate process with core dump9SIGKILLForcibly killing a process24SIGSTOPPausing the process26SIGCONTRuns a stopped process
File Permission:
1. chmod octal file : During working out with database on a unix platform we would face permission issue while trying to execute a file ,update a file or even read a file for any operation.
Since the root login for unix system would not be provided to a dba in a genuine scenario we need to have adequate permissions of the file we require.
chmod will change the permission of the file which would restrict the acess level for user,group,world as per the octal provided during the use of chmod command.
eg:
chmod 755 <filename> will give the current user full permission to read,write and execute the file ,whereas will give the group of the user and any other user full permission to read and execute the file.
The permission 755 can be understood if we look at the below break down of the octal code
user group world
r w x r w x r w x
7 5 5
111 101 101
In binary code representation of 7 5 5, 1 would represent true and 0 false , so we can make out for user a 755 would provide read,write and execute permission whereas for group and world it would provide read and execute permission.
2.chown <group:user> <file>:chown is used to change the ownership of the file to a particular user(either a user ID or a login name from /etc/passwd) of a particular group.This is helpful in cases when we would like to define the permission levels for a file or only want it to be used by a particluar user or group.
Searching:
The analyzing of log files and error files is a hectic but critical task in case of an outage or issue on the database.To speed up the analyzing part and finding the related data from chunks of log files can be achieved if the dba has a good hold on searching utilities of unix.Below are some important searching commands
1. grep pattern file :Search for pattern in file
2. grep -r pattern dir :Search recursively for pattern in dir
3. command | grep pattern :Search pattern in the output of a command
4. locate file :Find all instances of file
5. find . -name filename :Searches in the current directory (represented by a period) and below it, for files and directories with names starting with filename
6. pgrep pattern :Searches for all the named processes , that matches
System Info
The system commands would be used on a more frequent basis since the OS helath on which our database instance is running is equally important as the database health.The below commands can be used to extract OS level informations
1. date :Show the current date and time
2. cal :Show this month's calender
3. uptime :Show current uptime
4. w :Display who is on line
5. whoami :Who you are logged in as
6. finger user :Display information about user
7. uname -a: Show kernel information
8. cat /proc/cpuinfo :Cpu information
9. cat proc/meminfo :Memory information
10. man command :Show the manual for command
11. df :Show the disk usage
12. du :Show directory space usage
13. free :Show memory and swap usage
14. whereis app :Show possible locations of app
15. which app: Show which applications will be run by default
Compression
To avoid space congestion on the system which may inturn result in choking the required space for the database to expand or function, we need to archive our old files.Compression of files present on the filesystem is the best way of archiving presently unwanted files.Following are compression commands
1. tar cf file.tar file Create tar named file.tar containing file
2. tar xf file.tar Extract the files from file.tar
3. tar czf file.tar.gz files Create a tar with Gzip compression
4. tar xzf file.tar.gz Extract a tar using Gzip
5. tar cjf file.tar.bz2 Create tar with Bzip2 compression
6. tar xjf file.tar.bz2 Extract a tar using Bzip2
7. gzip file Compresses file and renames it to file.gz
8. gzip -d file.gz Decompresses file.gz back to file
Shortcuts
There is no shortcut to success, but to attain efficiency in our task on a unix/linux OS shortcuts can come handy.Below are some useful shortcut commands :
1. ctrl+c Halts the current command 2. ctrl+z Stops the current command, resume with fg in the foreground or bg in the background 3. ctrl+d Logout the current session, similar to exit 4. ctrl+w Erases one word in the current line 5. ctrl+u Erases the whole line 6. ctrl+r Type to bring up a recent command 7. !! Repeats the last command 8. exit Logout the current session Unix/Linux
