- How to check the
utilisation of each cores: mpstat -P ALL 1 & lscpu or cat
/proc/cpuinfo
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- ps -aeF
gives the details of which core ID is being used for a process.
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- top -H -p => gives all the
details of threads of all the processes.
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- lsof -t => Gives the
PID of a file name.
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- netstat -a => all ; listening +
established; -n => suppress host/port name resolution; -t => only tcp ;
-p => program name; -r routing; -i interface
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- Find files smaller than 2K: find -type f
-mindepth 2 -size -1c
- Find files which are not older than 2 days: find -type f -mtime -2
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- stat zzz (Gives all the statistics of a
file); stat %i ; %F; %G; %U; %b ; atime => when it was last accessed ,
mtime => when the file was last modified, ctime when the file was last changed (changed means file attributes
were changed)
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- Unix File system: A directory has name
& a number; number refers to a
inode location where Group/User ID, permissions, files/directory, references
to data blocks are presents & the actual data resides in data blocks.
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- chmod rwx+ugo or chmod u+rwx,g+xr,o+r or chmod u=rwx,g=xr,o=r or chmod 776
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- PS1="[\u@\h]" ==> set the
primary terminal as [user@hostname]
=> set the primary terminal name
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- pr => minor formatting of the file.
-
- add line :set backupcopy=yes in /var/home/root/.vimrc for 'crontab: no changes made to crontab' error
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- in VI, d^ => delete from curser to
start; d$ => delete from the curser to end ; yy => copies the current
line; p => paste the copied line
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- vi => :w filename (copy to
filename):2r filename (paste lines from the filename to curent after 2nd
line) :e filename (Open another filename) :e # (toggle between two files)
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- ulimit is used to limit the file size, no of
open files,cpu time, max user processes. ulimit -a gives the details of what
those attributes are set
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core file size (blocks, -c) unlimited |
data seg size (kbytes, -d) 24655 |
scheduling priority (-e) 0 |
file size (blocks, -f) unlimited |
pending signals (-i) 159878 |
max locked memory (kbytes, -l) 24655000000000 |
max memory size (kbytes, -m) unlimited |
open files (-n) 1024 |
pipe size (512 bytes, -p) 8 |
POSIX message queues (bytes, -q) 819200 |
real-time priority (-r) 0 |
stack size (kbytes, -s) 10240 |
cpu time (seconds, -t) unlimited |
max user processes (-u) 1024 |
virtual memory (kbytes, -v) unlimited |
file locks (-x) unlimited |
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- Execution sequece in unix,when first log
into .bash_profile, then .bash_login, then .bashrc
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