Search and edit text documents, and assign to variable in Mac terminal

Question

So if I saved system_profile to a text document, how would I be able to delete all but one section? Or delete quotes around it? Then how would I assign certain text to a variable to check certain things?

Example: If I save system_profile to a text document, how would I search through to find how much ram I have, and assign that to the variable 'ram'? Also, could I have it search for and delete certain characters? For example have a script delete all quotation marks?

Answer 1

You can search for words in a file using grep.

Example:

cat system_profile | grep ram

This will return the line in system_profile that contains the pattern "ram". You'll probably need to run the command and look at the return before you can develop an understanding of what to do next. If all you want is a portion of the file, you can perform a search and redirect your output to a new file.

Example:

cat system_profile | grep ram -A 5 > system_ram

This will give you the line that contains "ram" and the five lines after it.

You can replace characters thru the utility sed.

Example:

sed -i 's/old/new/g' system_profile

To eliminate double quotes ("):

sed -i 's/"//g' system_profile

Answer 2

I'm not entirely sure how to select between different occurrences, but hopefully this will help.

x=$(cat system_profile | grep ram -A 5)

The above code will save the line containing ram and the next 5 lines after it. For getting lines before, use -a instead of -A.

I guess grep supports selecting a limited number of lines (i.e. stop after the first occurrence of ram). If that is what you are looking for, use the -m 1 (where one is the number of occurrences to find before stopping) option for grep.

Alternatively, you can modify your grep search if the two (or more) lines getting selected are not identical. Just change ram to whatever you need to match (put it in quotes if it is more than one word)