Skip to main content

Linux bash script basic string manipulation

  
How to concatenate strings in bash script?

Example: Jan 1 2015

If you just need to take the first letter or the first character:

------------------------------------------------------------ 
stringvar="Jan 1 2015"

first_letter_only=${stringvar:0:1}

echo "$first_letter_only"

#result would be "J"
------------------------------------------------------------

${stringvar:0:1} - "0" tells bash to start cutting the string at zero position
                           - "1" means get only 1 character

To get 2015 from the same string above:
------------------------------------------------------------
stringvar="Jan 1 2015"

get_year_only=${stringvar:6:4}

echo "$get_year_only"

#result would be "2015"
------------------------------------------------------------

How to get the position of the string?

Count from the first character start with “0” zero, up to the last character on the string include spaces, symbols or whatever character is on the string.

When assigning variable or string don't put a space from the "=" equals sign to the string.

Like: stringvar= "Jan 1 2015"  -- this would result to error


Observer also the curvely braces when there is a process involved and the result is assigned to the variable.

get_year_only=$(stringvar:6:4) - open and close parenthesis is wrong


This is the basic and simple stuff to manipulate string on bash script.

As your mileage vary through the years of course, things will get exciting always. But if you are just beginning to grasp the world of bash scripting then start the basic right and understand it thoroughly, then the next will be easy.


Cheers.. Enjoy.. till net time….

Linux Android App cheat sheet:
https://play.google.com/store/apps/details?id=com.LinuxMobileKit

Comments

Popular posts from this blog

Copy a single file using robocopy

Copy a single file using robocopy from a local folder to a shared folder on the network.
A simple rule of thumb before any disaster strike, don't interchange the source and the destination.

If source and destination is mistakenly reverse, files might get overwritten. To avoid any loss of data do a test with a dummy file to ensure things work perfectly.
Robocopy [source][destination]   [file to be copied]
robocopy c:\local_c_folder  \\PC_network\shared_folder   file_to_be_copied_xx.txt
The command will be completed successfully provided the network access right has no issues.

Robocopy works quite good on large files. A simple copy or xcopy command will also work but the speed might vary.

However, if the file (ex. an ISO file) and is more than 4GB and the filesystem  of the thumbdrive or the storage is FAT system, then robocopy or any methods of copying will not work. Since FAT has a file size limitation of less than 3GB.

Robocopy is free it can be accessed from command line. No ne…

WMIC List printers

WMIC comes handy if you are a command line junkie.

To list printers via command line type:

wmic printer get name  = = = this will list all the printers installed on a workstation

To list the printer name and the port name of the printers, type this command:

wmic printer get name, portname

Type this command below to list the printer drivers:

wmic printer get name, drivername

To get the device id:

wmic printer get name, deviceid

You can deploy a batch file startup script to check which printer is installed on the computers and redirect the output to a shared folder.

PowerShell can also be used in conjunction with WMIC command:
http://quickbytesstuff.blogspot.sg/2015/11/powershell-list-printers-of-remote.html


To see more WMIC tips, click on WMIC label below.

Cheers!!!

Linux Android App cheat sheet:
https://play.google.com/store/apps/details?id=com.LinuxMobileKit

WMIC get computer name

WMIC get computer model, manufacturer, computer name and  username.
WMIC is a command-line tool and that can generate information about computer model, its manufacturer, its username and other informations depending on the parameters provided.
Why would you need a command line tool if there’s a GUI to check?
If you have 20 or 100 computers, or even more. It’s quite a big task just checking the GUI to check the computer model and username.
If you have remote computers, you need to delegate someone in the remote office or location to check.
Or you can just write a batch file or script to automate the task.
Here’s the code below on how get computer model, manufacturer and the username.
Open an elevated command prompt and type:
wmic computersystem get "Model","Manufacturer", "Name", "UserName"
Just copy and paste the code above, the word “computersystem” does not need to be change to a computer name.
A sample output below will be generated if the co…