linux Quries

Q: How to delete files older than N number of days ? (Useful in delete log, trace, tmp file )
find . -name ‘*.*’ -mtime +[N in days] -exec rm {} \; ( This command will delete files older then N days in that directory, always good to use it when you are in applcsf/ tmp,out,log directory)
Q: How to list files modified in last N days
find . -mtime - -exec ls -lt {} \;
So to find files modified in last 3 days
find . -mtime -3 -exec ls -lt {} \;
Q: How to sort files based on Size of file ? ( useful to find large files in log directory to delete in case disk is full )
ls -l | sort -nrk 5 | more
Q: How to find files changed in last N days (Solaris)
find -mtime -N -print
Q: How to extract cpio file
cpio -idmv < file_name (Don’t forget to use sign < before file name) Q: How to find CPU & Memory detail of linux cat /proc/cpuinfo (CPU) cat /proc/meminfo (Memory) Q: How to find if Operating system in 32 bit or 64 bit ? For solaris use command isainfo -v If you see out put like 32-bit sparc applications That means your O.S. is only 32 bit but if you see output like 64-bit sparcv9 applications 32-bit sparc applications above means your o.s. is 64 bit & can support both 32 & 64 bit applications Q: How to find if any service is listening on particular port or not ? netstat -an | grep {port no} For example if you know that OID is running on 389 port so to check if OID services is listening or not then use netstat -an | grep 389 Q: How to find Process ID (PID) associated with any port ? This command is useful if any service is running on a particular port (389, 1521..) and that is run away process which you wish to terminate using kill command lsof | grep {port no.} (lsof should be installed and in path) Q: How to change a particular pattern in a file ? Open file using vi or any other editor, go in escape mode (by pressing escape) and use :1,$s/old_pattern/new_parameter/gc ( g will change globally, c will ask for confirmation before changing ) Q: How to find a pattern in some file in a directory ? grep pattern file_name ( to find pattern in particular file ) grep pattern * ( in all files in that directory ) If you know how to find a pattern in files in that directory recursively please answer that as comment Q: How to create symbolic link to a file ? ln -s pointing_to symbolic_name e.g. If you want to create symbolic link from a -> b
ln -s b a
(Condition:you should have file b in that directory & there should not be any file with name a)
Q: How to setup cronjob (cronjob is used to schedule job in Unix at O.s. Level )
crontab -l( list current jobs in cron)
crontab -e ( edit current jobs in cron)
_1_ _2_ _3_ _4_ _5_ executable_or_job
Where
1 - Minutes (0-59)
2 - Hours ( 0-24)
3 - day of month ( 1- 31 )
4 - Month ( 1-12)
5 - A day of week ( 0- 6 ) 0 -> sunday 1-> monday
e.g. 0 3 * * 6 Means run job at 3AM every saturday
This is useful for scheduling ftp, rman backup or removed old log files regularly.