I have a dataset with subjects of which the SUVr is calculated and put on the 3rd line of a txtfile, specific to each subject (so every subject has a different txtfile containing the SUVr). My question is: How can I get the 3rd line (which is the SUVr value) of every subjects' txtfile and place them in a new txtfile, so all the SUVRs of every subject are placed in one txtfile? I'm using the Linux terminal to do this. Thank you very much!
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1Use ```grep``` for that lines you wanna ```>>``` to a file. No example provided - No exact answer possible – koyaanisqatsi May 05 '21 at 16:23
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for file in $(find . -type f); do sed '3q;d' $file; done > output.txt
Some explanation about the command parts:
find . -type f: list all files- If you need to filter by extension:
find . -type f -name "*.txt"
- If you need to filter by extension:
sed '3q;d' filename: prints the 3rd line of the file- See more: Bash tool to get nth line from a file
> output.txt: write tooutput.txt(use>>if you want to append)
Paulo Amaral
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awk works well for this also.
awk '3 == FNR { print $0; }' /path/to/$files.* >found
FNR is File Number of Records, so it grabs the 3rd line from each file without executing over and over, or needing a find, etc.
Paul Hodges
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