Commands by acirulli (4)

What's this? is the place to record those command-line gems that you return to again and again. That way others can gain from your CLI wisdom and you from theirs too. All commands can be commented on, discussed and voted up or down.

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Create a new file

shows history of logins on the server
perfect on a crashed system where you can't use commands like last. for investigation purposes wtmp file can be copied over to a different server and read with utmpdump

create SQL-statements from textfile with awk
inputfile.txt is a space-separated textfile, 1st column contains the items (id) I want to put into my SQL statement. 39 = charactercode for single tick ' $1 = first column If inputfile.txt is a CSV-file separated by "," use FS= to define your own field-separator: $ awk 'BEGIN {FS=","; }{printf "select * from table where id = %c%s%c;\n",39,$1,39; }' inputfile.txt

find and replace tabs for spaces within files recursively

Continue a current job in the background

Combines an arbitrary number of transparent png files into one file
This one liner; combines all sequentially numbered files; in this example IMG_0001.png to IMG_1121.png by generating the shell script, making the shell script executable and then running the shell script to combine the 1121 png into a single png file named _final.png tested on Mac OS X 10.6.3 with ImageMagick 6.5.8-0 2009-11-22 Q16

Randomize lines in a file
Works in sort (GNU coreutils) 7.4, don't know when it was implemented but sometime the last 6 years.

Play 89.3 @TheCurrent and get system notifications on song changes.
Plays the mp3 stream of The Current as a background job. When you are done run: $ fg %1 then to exit Quite possible with Growl for mac I'd guess, although have not tried. Libnotify needed for notification, stream will still work otherwise

Get a list of IP Addresses that have failed to login via SSH
This command shows a sorted list of the IP addresses from which there have been authentication errors via SSH (possible script kiddies trying to gain access to your server), it eliminates duplicates so it's easier to read, but you can remove the "uniq" command at the end, or even do a "uniq -c" to have a count of how many times each IP address shows in the log (the path to the log may vary from system to system)

Speed up builds and scripts, remove duplicate entries in $PATH. Users scripts are oftern bad: PATH=/apath:$PATH type of thing cause diplicate.
Thanks to the authors of: $ awk '!x[$0]++' and the author of: $ joinargs() { (local IFS="$1"; shift && echo "$*") } and others, we can have a fast Linux or android. IMPORTANT if you find a priority order problem in PATH you can push a path directory to the front without duplication as follows: $ PATH=/bin:$PATH then ... Check duplication with: $ echo $PATH|tr : '\n'|sort|uniq -d Finally do a very neat line by line list of $PATH: $ echo "${PATH//:/$'\n'} The speed up is very noticeable for android, and builds on Linux Ubantu are much faster with make and scripts. I will update the command on request. Timothy from SONY

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