Skip to main content

Use Linux Grep in Bash Script



Grep is a useful command in Linux to filter desired strings or values or to match string pattern.

Type: "man Grep" on Linux terminal window to dig more about Grep command.

Script below is a simple way on how Grep can be used on a script.

Script also shows and performs basic calculation to get desired number of days.

Ls command in Linux is to list directory contents.

If dealing with a large or huge data, Ls alone can't be a handy tool.

So "Ls" command combined with "Grep" can be a good handy tool.

For more complex scenario "RegEx" will come into play, but "RegEx" will be too much for a newbie.

So mileage may vary using "RegEx".

So it's better to start with Grep and get a hang of it and move to "RegEx" to gain more.

Script below, will list files on a directory.

All files on a directory which has a time stamp of yesterday's date from the current date.

xMinus variable can be adjusted or set, so if it is set to "2". It will list files which has a time stamp 2 days earlier from current date.


Here's the simple bash script:

================================
#!/bin/sh

getDate="$(date +"%d")"

getMonth="$(date +"%b")"

#Will display the date and month; result of above commands

echo $getDate

echo $getMonth

xMinus=1

# $((calculation variables)) surround the arithmetic operation with $((calculate here))

# 10# tell bash to treat the variable as numeric

# since value of xMinus is set to 1 will get yesterday's date from today's date

$xbackupDate=$((10#$getDate-10#$xMinus))

if [ "$getDate" -le "9" ]; then

#space is the trick here

#Linux will have single space in between Month and Day if the date is less than 9

xDgrep="$getMonth  $xbackupDate"

elif [ "$getDate" -ge "10" ]; then

#Linux will have two spaces in between Month and Day if the date is greater than 9

xDgrep="$getMonth $xbackupDate"

fi

for f in $(ls -l /home/mybackupFiles/NASBak | grep "$xDgrep" )

do

# redirect read files

echo $f >> "xFiles.txt"

# or do a cp command to copy files or whatever process desired

done



To dig more about Linux "Grep", this one is a great site:
http://www.cyberciti.biz/faq/howto-use-grep-command-in-linux-unix/


Cheers till next time!!

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

Get Printer Driver Path and Name:
https://quickbytesstuff.blogspot.com/2020/05/powershell-get-printer-name-and-driver.html


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

Cheers!!!

=======

Catholic Rosary Guide  for Android: Pray the Rosary every day, countless blessings will be showere…

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…