Compare files ignoring a field or column using Process Substitution
Using Process Substitution method, two streams of data can be used with `diff`. This allows pre-processing of files to drop some part (e.g. a column/record per ...
Category: Bash
postfix : Configure outgoing relay server
Add name of outgoing/relaying mailhost as `relayhost` in `/etc/postfix/main.cf` and restart postfix.
Find the process monopolizing the CPU without using “top”
`ps -eo pcpu,pid,ruser,args | sort -r -k1 | less` provides in reverse sort order the `pid` that is taking up most of `pcpu` and the `ruser` (real user) with `ar...
bash : grep for pattern from certain location in the file
Using dd, the file can be sliced and then grep can be applied for the pattern on that slice.
bash : search multiple file patterns using single find command
Using a combination of patterns with "-o" and/or -"a" (which OR the pattern or AND the pattern) in find command, one can search for various patterns or combine ...
Howto rollover a file when size exceeds using unix find
Using -size and -exec flags of find command, one can easily find when the logfile has grown above the threshold and move it to another name in one shot.
Unix : find affected by current working directory
Many Unix variants (including latest Solaris 11 Express) use a version of find that first looks for current working directory. And if that current working direc...
bash : Count number of recurrence of lines
Using sort and uniq commands, one can count number of recurrences of records in a file.
bash : Self redirect of Script’s output to a file
Using shell builtin exec, ouput and error output streams of a script can be redirected just like ">" or ">>" operators.
How to find current runlevel on unix system
Linux provides a utility called runlevel but "who -r" is a portable solution which is available across various Unixes.