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Get a list of the erroring cifs entries in fstab
It disturbs me when my logwatch report tells me a share or machine has disappeared, esp as mount isn't telling me what's gone. This command outputs to stderr the erroring cifs entries from fstab.

Optimal way of deleting huge numbers of files
Optimal way of deleting huge numbers of files Using -delete is faster than: $ find /path/to/dir -type f -print0 | xargs -0 rm $ find /path/to/dir -type f -exec rm {} + $ find /path/to/dir -type f -exec rm \-f {} \;

calulate established tcp connection of local machine

Show all listening and established ports TCP and UDP together with the PID of the associated process
Easy to remenber. Fot TCP only use: netstat -plant

Generate random number with shuf
If you don't have seq or shuf, bash can be used.

External IP (raw data)
can be used in script like : echo $(wget -qO- http://utils.admin-linux.fr/ip.php)

cat a bunch of small files with file indication
If you have a bunch of small files that you want to cat to read, you can cat each alone (boring); do a cat *, and you won't see what line is for what file, or do a grep . *. "." will match any string and grep in multifile mode will place a $filename: before each matched line. It works recursively too!!

Display email addresses that have been sent to by a postfix server since the last mail log rollover
This assumes your mail log is /var/log/mail.log

recursive search and replace old with new string, inside files
xargs deals badly with special characters (such as space, ' and "). To see the problem try this: touch important_file touch 'not important_file' ls not* | xargs rm Parallel https://savannah.nongnu.org/projects/parallel/ does not have this problem.

Log colorizer for OSX (ccze alternative)
Download colorizer by @raszi @ http://github.com/raszi/colorize


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