Commands by BrentWoods (0)

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Use a var with more text only if it exists
See "Parameter Expansion" in the bash manpage. They refer to this as "Use Alternate Value", but we're including the var in the at alternative.

Get the size of all the directories in current directory (Sorted Human Readable)
as per eightmillion's comment. Simply economical :)

Save the list of all available commands in your box to a file
When you press TAB twice in your prompt, bash tells you something like "Display all 4567 possibilities? (y or n)" But when you press "y" you only get the list in the terminal output and, if you want to save it to a file, you have to copy it by hand from the vterm screen. With this utility you save the list to a file or pipe it to another command at will You can use the file saved list to grep for a particular pattern, useful if you are searching for a command but you only remember a few letters

multiline data block parse and CSV data extraction with perl
extract data in multiline blocks of data with perl pattern matching loop

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

check site ssl certificate dates
remotely connects to an https site, fetches the ssl certificate and displays the valid dates for the cert

Insert a line at the top of a text file without sed or awk or bash loops
Yet another way to add a line at the top a of text file with the help of the tac command (reverse cat).

Set laptop display brightness
Run as root. Path may vary depending on laptop model and video card (this was tested on an Acer laptop with ATI HD3200 video). $ cat /proc/acpi/video/VGA/LCD/brightness to discover the possible values for your display.

Which processes are listening on a specific port (e.g. port 80)
swap out "80" for your port of interest. Can use port number or named ports e.g. "http"

Use find to get around Argument list too long problem
Can be used for other commands as well, replace rm with ls. It is easy to make this shorter but if the filenames involved have spaces, you will need to do use find's "-print0" option in conjunction with xargs's "-0" option. Otherwise the shell that xargs uses to execute the "rm" command line will treat the space as a token separator, thereby treating the name as two (or more) names.

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