Problem scenario
You want a script to test if a file is in a specific location or not. You are using Linux. What should you do?

Solution
Use this script (but modify “/path/to/file” to be the path and name of the file you are searching for):

if [ -f “/path/to/file” ]
then
echo “file exists”
else
echo “file does not exist”
fi  » Read more..

Problem scenario
You want a non-terminating (or hanging) Linux command that never finishes to go to the background. You want to use the next command line prompt. The process starts from a command you issue at the command line. How do you do you get to the next prompt?

Solution

1. This will suspend the process momentarily. Hold control and tap “z.” Ctrl-z

2. The above command will result in something like this:
   [555]+ Stopped python3 goodprogram.py

Craft a command like this,

 » Read more..

Problem scenario
You run a grep command but it fails. You get a message about “memory exhausted.” What should you do?

Solution
Possible Solution #1
If you are comparing two files line-by-line, try reversing the order of the file arguments for the grep command. For example try these two versions:

grep -f a.txt b.txt
grep -f b.txt a.txt

If the file in the left argument is smaller,

 » Read more..

Problem
You want to search a file for words that include a given pattern. You want to use grep to return the word that matches a pattern, and you do not want to return the entire line that matches a pattern. You want to return the exact word without the leading space or trailing space. What do you do?

Solution
Try this command:

cat foobar.txt | tr “//” “\n” | grep “coolpattern”

The above,

 » Read more..