IT/Software/Command Line

Welcome to the dark world where most IT people live

• This is a gui free world
  • If you don't know what a gui is please quietly close the page and go buy a slurpee
  • If you don't know what a slurpee is we feel sorry for you.

Basic Commands

Find

This will help you find files and/or folders. Its power is amazing. It is often used in conjunction with commands. First find something and then do something.

find directory -user username

Directory is relative unless you specify absolute

Changing Ownership

There are many ways to do this. Half of them may be more clever.

sudo chown walt:walt /path/to/filename

This will make the file filename belong to the user walt and the group walt. Usually we change the group and user at the same time.

OR

sudo chown user:group /path/to/directory/

This changes only the directory to user and group specified

Adding the -R flag after the chown will recurse into directories and files.

sudo chown -R . . .

• We are not sure why the capital r is needed in some cases. But it is here.

Changing Permissions

This is very similar except we use chmod instead of chown

sudo chmod 644 /path/to/file or path/to/directory/

Adding the -R flag does the same as above.

Change all files recursively to 644

find /var/www/html/moodlecnx/ -type f -exec chmod 644 {} \;

Change all directories recursively to 755

find /var/www/html/moodlecnx/ -type d -exec chmod 755 {} \;

Mount and Unmount

iso files

sudo mkdir /mnt/iso

sudo mount -o loop Win10_2004_English_x64.iso  /mnt/iso

Symlinks

This allows you to click on a folder or directory and actually end up somewhere else.

For example if a user can't figure out how to get to the Documents folder from Dolphin.
ln -s /real/file/or/folder/path /path/to/link

The link can't already exist.

the path can be a file or directory.

Delete all files in folder tree

This will find all files under the parent directory(absolute) and recursively delete them.

It will not delete hidden files.

find  ~/msgcnxFiles/Teacher/Science/Biology/For\ Upload/ -type f -delete

Printing

lp is the classic

lp filename will print the file to the default printer with the default settings

lp -n 3 /path/*.pdf

Much time has been invested in learning this.

Make sure you install the printer correctly or you will get strange errors.

Stay away from "driverless" if you can.

List the default destination

lpstat -d

List the available printers

lpstat -d -p

Print Portrait two sided.

lp -o sides=two-sided-long-edge

3 copies of any pdf file in that path.

-P page-list Specifies pages  to  print  in  the  document.   The  list  can contain a list of numbers and ranges (#-#) separated by commas, e.g.,

            "1,3-5,16".  The page numbers refer to the output pages and not the document's original pages

Rename

• This function has many many option. We can only begin here.
• Below is an example where we prepend a 0 onto file names so that they order correctly on all OSes
• This works in the current working directory

rename -e 's/\d+/sprintf("%02d",$&)/e' -- *.jpg