I have a directory containing log files. This command delete all but the 5 latest logs. Here is how it works:

* The ls -t command list all files with the latest ones at the top

* The awk's expression means: for those lines greater than 5, delete.

This helped me find a botnet that had made into my system. Of course, this is not a foolproof or guarantied way to find all of them or even most of them. But it helped me find it.

shows also time if its the same year or shows year if installed before actual year and also works if /etc is a link (mac os)

Show time and date when you installed your OS.

use manpages, they give you "ultimate commands"

"ls -SshF --color" list by filesize (biggest at the top)

"ls -SshFr --color" list by filesize in reverse order (biggest at the bottom)

Compile *.c files with "gcc -Wall" in actual directory, using as output file the file name without extension.

1. find file greater than 10 MB

2. direct it to xargs

3. xargs pass them as argument to ls

use the locate command to find files on the system and verify they exist (-e) then display each one in full details.

This allows the output to be sorted from largest to smallest in human readable format.

This command will find the biggest files recursively under a certain directory, no matter if they are too many. If you try the regular commands ("find -type f -exec ls -laSr {} +" or "find -type f -print0 | xargs -0 ls -laSr") the sorting won't be correct because of command line arguments limit.

This command won't use command line arguments to sort the files and will display the sorted list correctly.

Ever need to output an entire directory and subdirectory contents to a file? This is a simple one liner but it does the trick every time. Omit -la and use only -R for just the names

Renames all the jpg files as their timestamps with ".jpg" extension.

Useful for deleting old unused log files.

I'm working in a group project currently and annoyed at the lack of output by my teammates. Wanting hard metrics of how awesome I am and how awesome they aren't, I wrote this command up.

It will print a full repository listing of all files, remove the directories which confuse blame, run svn blame on each individual file, and tally the resulting line counts. It seems quite slow, depending on your repository location, because blame must hit the server for each individual file. You can remove the -R on the first part to print out the tallies for just the current directory.

Output manpage as plaintext using cat as pager: man -P cat commandname

And redirect its stdout into a file: man -P cat commandname > textfile.txt

Example: man -P cat ls > man_ls.txt

Find when debian packages were installed on a system.

This command finds the 5 (-n5) most frequently updated logs in /var/log, and then does a multifile tail follow of those log files.

Alternately, you can do this to follow a specific list of log files:

sudo tail -n0 -f /var/log/{messages,secure,cron,cups/error_log}

Creates a PDF (over ps as intermediate format) out of any given manpage.

Other useful arguments for the -T switch are dvi, utf8 or latin1.