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grep tab chars
mixing tabs and spaces for indentation in python would confuse the python interpreter, to avoid that, check if the file has any tab based indentation. "^V" => denotes press control + v and press tab within quotes. $ cat improper_indent.py class Tux(object): print "Hello world.." $ grep " " improper_indent.py print "Hello world.."

Find usb device
I often use it to find recently added ou removed device, or using find in /dev, or anything similar. Just run the command, plug the device, and wait to see him and only him

list block devices
Shows all block devices in a tree with descruptions of what they are.

SVN Clean
Removes all unversioned files and folders from an svn repository. Also: $ svn status --no-ignore | grep ^I | awk '{print $2}' | xargs rm -rf will remove those files which svn status ignores. Handy to add to a script which is in your path so you can run it from any repository (a la 'svn_clean.sh').

File rotation without rename command
Rotates log files with "gz"-extension in a directory for 7 days and enumerates the number in file name. i.e.: logfile.1.gz > logfile.2.gz I needed this line due to the limitations on AIX Unix systems which do not ship with the rename command.

Check whether laptop is running on battery or cable
The original proc file doesn't exist on my system.

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

list files recursively by size

generate random password
generate password

Count items in JSON array
Pipe any JSON to jq, then count with the appropiate expression and use the | length on the array


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