bash script remove non-printable special characters/white space

In bash you test like this for problems that can be caused by non-printable characters since if you don't know how to identify it because it basically breaks your script.

echo "url=$url" should print something like this normally if you have properly formatted input/text:

url=::http://someaddress.com::

But if you have some weird hidden characters (not visible in a text editor of any sort you'll get something like this
::l=::http://someaddress.com

How come it doesn't print as expected?
There are hidden/non-printable characters, usually ASCII code I believe that cause unexpected behavior like above and wreaks havoc on many scripts/programs who didn't realize this since there are non-printable characters.

There is a program in Linux that takes care of it called "tr"
If I read data line by line using cat, I now use "tr" to filter all the non-printable characters (I use it line by line and not the entire file since this would remove things like linebreaks and then you have a text file that becomes a single line).

Here is how you'd fix a bad variable (one with non-printable/special characters):

url=`echo "$url"|tr -dc ‘[:print:]‘


Tags:

bash, printable, characters, spacein, echo, quot, url, formatted, input, text, http, someaddress, visible, ll, doesn, ascii, wreaks, havoc, scripts, programs, didn, linux, tr, filter, linebreaks, variable, dc, lsquo,

Latest Articles

  • Debian and Netplan
  • CentOS 8 how to restart the network!
  • CentOS 8 how to convert to a bootable mdadm RAID software array
  • ADATA USB Thumb Drive Issues
  • KMODE EXCEPTION NOT HANDLED - QEMU/KVM Won't Boot Windows 2016 or 10 Image or Physical Machine
  • Linux Mint / Ubuntu / Debian Mate Disable Guest Session and Hide Usernames on Lightdm Login screen GUI
  • SSH How To Create Public/Private Key Pair and with a Larger Keysize than 2048 bits
  • selenium.common.exceptions.WebDriverException: Message: Can not connect to the Service geckodriver
  • python ModuleNotFoundError: No module named 'bs4' even though you have the module
  • ssh how to connect using a SOCKS 5 proxy with nc and proxycommand
  • Enable AMDGPU Linux Driver
  • apache symlinks denied even with followsymlinks
  • chown how to change ownership on a symlink
  • how to use ifplugd in Linux to execute a command or script when a NIC cable is unplugged or plugged in
  • dd how to backup and restore disk images including compression with gzip
  • mpv / mplayer with Radeon / AMD GPU Video Card Driver enable VDPAU GPU Accelerated Video Decoding
  • Wordpress Reset Blog User Password from MySQL Using Linux Bash and not PHPMyadmin
  • Ubuntu Linux Mint Debian xorg performance and tear-free tuning for AMD Radeon Based Cards
  • Centos 7 Stopped and Disabled Firewalld and ports still blocked
  • MariaDB / MySQL Reset Root Forgotten Password on Centos 7