Commands by karlnwilson (0)

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Rename files in batch

Convert seconds to [DD:][HH:]MM:SS
Converts any number of seconds into days, hours, minutes and seconds. sec2dhms() { declare -i SS="$1" D=$(( SS / 86400 )) H=$(( SS % 86400 / 3600 )) M=$(( SS % 3600 / 60 )) S=$(( SS % 60 )) [ "$D" -gt 0 ] && echo -n "${D}:" [ "$H" -gt 0 ] && printf "%02g:" "$H" printf "%02g:%02g\n" "$M" "$S" }

A command to copy mysql tables from a remote host to current host via ssh.
In the example above 3 tables are copied. You can change the number of tables. You should be able to come up with variants of the command by modifying the mysqldump part easily, to copy some part of remote mysql DB.

Find usb device in realtime
Using this command you can track a moment when usb device was attached.

Read and write to TCP or UDP sockets with common bash tools
Ever needed to test firewalls but didn't have netcat, telnet or even FTP? Enter /dev/tcp, your new best friend. /dev/tcp/(hostname)/(port) is a bash builtin that bash can use to open connections to TCP and UDP ports. This one-liner opens a connection on a port to a server and lets you read and write to it from the terminal. How it works: First, exec sets up a redirect for /dev/tcp/$server/$port to file descriptor 5. Then, as per some excellent feedback from @flatcap, we launch a redirect from file descriptor 5 to STDOUT and send that to the background (which is what causes the PID to be printed when the commands are run), and then redirect STDIN to file descriptor 5 with the second cat. Finally, when the second cat dies (the connection is closed), we clean up the file descriptor with 'exec 5>&-'. It can be used to test FTP, HTTP, NTP, or can connect to netcat listening on a port (makes for a simple chat client!) Replace /tcp/ with /udp/ to use UDP instead.

disk space email alert
put it in crontab to get an alert when / is over 89% utilization.

connects to a serial console
cu (call UNIX) establishes a full-duplex connection to another machine (*BSD) using a serial console. It becames more useful than screen if you have to send a BREAK signal. using cu just type "~#". $man cu http://www.openbsd.org/cgi-bin/man.cgi?query=cu&apropos=0&sektion=0&manpath=OpenBSD+Current&arch=i386&format=html

Write comments to your history.
A null operation with the name 'comment', allowing comments to be written to HISTFILE. Prepending '#' to a command will *not* write the command to the history file, although it will be available for the current session, thus '#' is not useful for keeping track of comments past the current session.

For a $FILE, extracts the path, filename, filename without extension and extension.
Useful for use in other scripts for renaming, testing for extensions, etc.

Count Files in a Directory with Wildcards.
Remove the '-maxdepth 1' option if you want to count in directories as well


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