Count the number of sub-directories

Another one liner that just counts the number of sub directories.

find ./*  -type d  | wc -l

Note – Remember to use ./* if you don’t want to include the current directory itself in the total.

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List packages by install date

A handy ‘one liner’ that lists all the packages installed on a RedHat system by the install date.

rpm -qa --qf $'%{INSTALLTIME}\t%{INSTALLTIME:date}\t%{NAME}\n' | sort -n -r -k1 | cut -f2,3
Sun 09 Jun 2019 17:26:04 BST systemd-sysv
Sun 09 Jun 2019 17:26:04 BST systemd-libs
Sun 09 Jun 2019 17:26:04 BST rsync
Thu 02 Nov 2017 12:49:32 GMT bzip2-libs
Thu 02 Nov 2017 12:49:13 GMT fontpackages-filesys
Thu 02 Nov 2017 12:49:13 GMT basesystem

This command uses format specifier to display the installed packages with a numeric date/time in the first field, a descriptive date/time in the second field, and the package name in the third field, all separated by tabs. The output is then sorted into date order using the numeric date field, and then just the second and third fields are displayed.

Note – You don’t need to specify a delimiter the output is formatted with tab between the fields which is the default delimiter used by sort and cut.

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Trouble with suspend/resume device

After restoring my laptop from a not so recent backup I found that it spent about 30 seconds waiting for the suspend/resume device.
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Script to set the MTU size in RedHat

The following script makes it easy to set the MTU size if you are using RedHat or CentOS 7.x, and has also been tested successfully on RedHat 6.x.
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Configure proxy settings for Git

If you are using git from behind a proxy then you will need to tell it what your proxy settings are.
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Determine MTU size using ping

Normally the MTU size should be set correctly using Path MTU discovery, but this may not always work.
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Installing a firewall on Debian (Lenny)

OK, I do know that ‘ufw’ isn’t actually a firewall in itself but I do find it useful and as some of you may have spotted I’m still using Debian (Lenny) on my Alphaserver.
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Get Debian version number

I use several different machines and while most of them run a flavour of Debian I can never remember exactly which version I’m running on which system.
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Listing all predefined values in GCC

If you need to check what built-in macros are already defined on the platform or version of GCC you are using you can use the following command to list all of them.
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Finding the closest matching named colour in Python

I needed to work out the closest named colour to an arbitrary hex colour code – so I wrote the following script which compares the specified hex colour code to each named colour in turn to determine which one is the closest match.
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