Tag Archives: convert

Merge multiple files into single PDF

I’m sure that we all had the need to send a single PDF file, maybe a signed contract. Yes, those 20 or more pages that you need to return, probably with just two of them filled up and signed.

Some PDF give you the ability to digitally sign them. But in my experience, most of them aren’t so modern.

So, what do I do?

I print ONLY the pages that I need to sign, scan them and here I am, with the need to “rebuild” the PDF, replacing the pages signed.

Example.
You have the file contract.pdf, with 20 pages and you need to sign page 10 and page 20.
The scan has a different resolution (or, even worse, it’s a different format, like jpg).

Here the command to make the magic happen:

convert contract.pdf[0-8] mypage10.jpg contract.pdf[10-18] mypage20.jpg -resize 1240x1753 -extent 1240x1753 -gravity center -units PixelsPerInch -density 150x150 contract_signed.pdf

The bit before -resize is pretty self explanatory. The bit after is a way to have the size of all pages fitting an A4 format, with a good printable resolution.

Of course, to make this happen, you need Linux (or WSL on Windows 10) and imagemagick installed.

Happy PDF’ing 🙂


Sources:
https://stackoverflow.com/questions/23214617/imagemagick-convert-image-to-pdf-with-a4-page-size-and-image-fit-to-page
https://www.shellhacks.com/merge-pdf-files-linux-command-line/

MySQL Engine – InnoDB vs MyISAM

InnoDB does locking on the row level and runs queries as nonlocking consistent reads by default

How to check the engine of tables for a database

 


Summary of Engines’ space utilised

 

Check MyISAM tables

NOTE:

When it converts from MyISAM to InnoDB, you will see in process list ‘copy to tmp table’. This has nothing to do with tmp_table_size or tmpdir. What it does, it goes inside your /var/lib/mysql/<dbname>/ and creates temporary files called like #sqlXXXX.frm and #sqlXXXX.ibd. Keep an eye on the size of the .ibd file to monitoring the progression. It should be roughly big like the sum of <table>.MYI and <table>.MYD. +~20%

 

Change all to InnoDB
https://support.rackspace.com/how-to/mysql-engines-myisam-vs-innodb/
When?
https://docs.dev4press.com/tutorial/wordpress/choosing-mysql-database-engine-myisam-or-innodb/
Quick answer: Always EXCEPT If you want to use FULLTEXT or SPATIAL indexes for some tables: in this case there is no choice and you must use MyISAM.

NOTE: FULLTEXT index support for InnoDB tables requires MySQL 5.6.4 or higherMariaDB 10.0.5 or higher
Highly recommend upgrading to MariaDB 10.0 as this is the 5.6 MySQL equivalent. It does not alter the data structures as 5.6 does and can be downgraded much more easily. It contains all the features of 5.6 plus more as well as being a drop-in replacement for MySQL in RHEL7.
I would point you to these KB articles:
https://mariadb.com/kb/en/mariadb-vs-mysql-features/https://mariadb.com/kb/en/mariadb/mariadb-vs-mysql-compatibility/Repositories: https://downloads.mariadb.org/mariadb/repositories/#mirror=somerset

Check if there are FULLTEXT or SPATIAL indexes:

Convert ALL MyISAM tables to InnoDB (all databases):

2 steps + backup

(one liner – CAREFUL!)

 

Convert MyISAM tables of a SPECIFIC database to InnoDB:

Backup and convert-file

NOTE: When it converts from MyISAM to InnoDB, you will see in process list ‘copy to tmp table’. This has nothing to do with tmp_table_size or tmpdir. What it does, it goes inside your /var/lib/mysql/<dbname>/ and creates temporary files called like #sqlXXXX.frm and #sqlXXXX.ibd. Keep an eye on the size of the .ibd file to monitoring the progression. It should be roughly big like the sum of <table>.MYI and <table>.MYD. +~20%

Convert EXT3 to EXT4

How to convert a EXT3 partition to EXT4 without reformatting

Then, make sure to change to ext4 any entries in /etc/fstab