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Remount an already-mounted filesystem without unmounting it
Necessary for fsck for example. The remount functionality follows the standard way how the mount command works with options from fstab. It means the mount command doesn't read fstab (or mtab) only when a device and dir are fully specified. After this call all old mount options are replaced and arbitrary stuff from fstab is ignored, except the loop= option which is internally generated and maintained by the mount command. It does not change device or mount point.

Recursively find top 20 largest files (> 1MB) sort human readable format
Search for files and list the 20 largest. $ find . -type f gives us a list of file, recursively, starting from here (.) $ -print0 | xargs -0 du -h separate the names of files with NULL characters, so we're not confused by spaces then xargs run the du command to find their size (in human-readable form -- 64M not 64123456) $ | sort -hr use sort to arrange the list in size order. sort -h knows that 1M is bigger than 9K $ | head -20 finally only select the top twenty out of the list

Backup a file with a date-time stamp
Appends the input file with the date format YYYY-MM-DD.bak. Also runs silently if you remove the -v on the cp at the end of the function.

get partitions that are over 50% usage

IP addresses connected to port 80
IP addresses and number of connections connected to port 80.

Optimal way of deleting huge numbers of files

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.

Url Encode
It only encodes non-Basic-ASCII chars, as they are the only ones not well readed by UTF-8 and ISO-8859-1 (latin-1). It converts all * C3 X (some latin symbols like ASCII-extended ones) and * C2 X (some punctuation symbols like inverted exclamation) ...UTF-8 double byte symbols to escaped form that every parser understands to form the URLs. I didn't encode spaces and the rest of basic punctuation, but supposedly, space and others are coded as \x20, for example, in UTF-8, latin-1 and Windows-cp1252.... so its read perfectly. Please feel free to correct, the application to which I designe that function works as expected with my assumption. Note: I specify a w=999, I didn't find a flag to put unlimited value. I just suppose very improbable surpass the de-facto 255 (* 3 byte max) = 765 bytes length of URL

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

Command to logout all the users in one command


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