Commands by lv4tech (10)

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diff output of two commands
This only works in bash

Delete all empty/blank lines from text file & output to file

Create a CD/DVD ISO image from disk.
Many like to use 'dd' for creating CD/DVD iso images. This is bad. Very bad. The reason this is, is 'dd' doesn't have any built-in error checking. So, you don't know if you got all the bits or not. As such, it is not the right tool for the job. Instead, 'reaom' (read optical media) from the wodim package is what you should be using. It has built-in error checking. Similarly, if you want to burn your newly creating ISO, stay away from 'dd', and use: $ wodim -v -eject /path/to/image.iso

Find and copy scattered mp3 files into one directory
I used this command to recursively gather all mp3 files that were previously imported into their own directories (sorted by band name) in Songbird.

format txt as table not joining empty columns
-n switch keeps empty columns If your distribution does not ship with a recent column version that supports -n you can use this alternative: perl -pe 's/(^|;);/$1 ;/g' file.csv | column -ts\; | less -S Change the delimiter to your liking.

GZip all files in a directory separately
It gzip each file in a directory separately

Create a bunch of dummy text files

bash/ksh function: given a file, cd to the directory it lives
fcd : file change directory A bash function that takes a fully qualified file path and cd's into the directory where it lives. Useful on the commadline when you have a file name in a variable and you'd like to cd to the directory to RCS check it in or look at other files associated with it. Will run on any ksh, bash, likely sh, maybe zsh.

Get AWS temporary credentials ready to export based on a MFA virtual appliance
You might want to secure your AWS operations requiring to use a MFA token. But then to use API or tools, you need to pass credentials generated with a MFA token. This commands asks you for the MFA code and retrieves these credentials using AWS Cli. To print the exports, you can use: `awk '{ print "export AWS_ACCESS_KEY_ID=\"" $1 "\"\n" "export AWS_SECRET_ACCESS_KEY=\"" $2 "\"\n" "export AWS_SESSION_TOKEN=\"" $3 "\"" }'` You must adapt the command line to include: * $MFA_IDis ARN of the virtual MFA or serial number of the physical one * TTL for the credentials

Send an http HEAD request w/curl


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