Ubuntu – How to use grep to find the next 7 characters after “temp1”

As the first comment said, without a view of your "file.txt" it is tough to know for sure we are getting this right.

My first thought was why don't you take the easy road? The >> will append, so create the one thing, add the rest.

cat file.txt | grep 'Values a' | cut -d' ' -f9 > a.csv
cat file.txt | grep 'Values b' | cut -d' ' -f9 >> a.csv
cat file.txt | grep 'Values c' | cut -d' ' -f9 >> a.csv
cat file.txt | grep 'Values d' | cut -d' ' -f9 >> a.csv

Then I wondered why do you run cat at all

grep 'Values a' file.txt | cut -d' ' -f9 > a.csv
grep 'Values b' file.txt | cut -d' ' -f9 >> a.csv
grep 'Values c' file.txt | cut -d' ' -f9 >> a.csv
grep 'Values d' file.txt | cut -d' ' -f9 >> a.csv

That works, but it puts the 4 things on new lines, rather than as comma separated values.

So I concentrated on stopping the new lines from being inserted, and getting a comma instead. awk can handle that.

grep 'Values a' file.txt | cut -d' ' -f9 | awk '{printf $0 ","}' > a.csv
grep 'Values b' file.txt | cut -d' ' -f9 | awk '{printf $0 ","}' >> a.csv

and so forth. That works, but right before I hit "send" I realized that I was following along with you using cut and we don't need to. awk can select the 9th thing.

grep 'Values a' file.txt | awk '{printf $9 ","}' > a.csv
grep 'Values b' file.txt | awk '{printf $9 ","}' >> a.csv

That worked on a little test case I made, maybe not on your test case.

If I were doing repeated greps on data to build a file, I'd probably prefer to keep it in separate lines, rather than in a big, complicated tangle like the other one recommended. So I don't think I'd go for a one liner, four lines I can understand is good enough.

If you are going to do more shell work like this, I suggest you get a copy of the old book Unix Power Tools. It has a lot of tricks like this.

Make sure you quote your expression.

$ grep ' \.pdf' example
grep .pdf

Or if there might be multiple spaces (we can't use * as this will match the cases where there are no preceding spaces)

grep ' \+\.pdf' example

+ means "one or more of the preceding character". In BRE you need to escape it with \ to get this special function, but you can use ERE instead to avoid this

grep -E ' +\.pdf' example 

You can also use \s in grep to mean a space

grep '\s\+\.pdf' example

We should escape literal . because in regex . means any character, unless it's in a character class.