stat243-week2lecture1.txt

stat243-week2lecture1.txt

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# Lecture
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# BASH stuff:

ls -tr *.R # gives you the list of the R files modified most recently (closest in time at bottom, farthest in time at top)
ls -tr *.R | tail - n 5 # last five things modified
ls -tr *.R | tail - n 5 | grep optim # look for files called 'optim' in the name

grep 'example.pdf' $(ls -tr *.R) # look for example.pdf in the stuff from inside $(.)
# xargs prepends a function and inserts the piped stuff into the argument part of the function
# note that the . here is searching for the wildcard regex . not the explicit . which would be /. (i think)
ls -tr *.R | tail -n 5 | xargs grep -l 'example.pdf' 

# Jared note
grep -r #r flag: searches recursively in subdirs that you feed it, even inside of text files!
grep -F #F flag: fixed string, no regex
grep -c #c flag: gives count of how many instances it gives

# file globbing: if you want to find all .R ext files but with some basic regex-y things with it:
ls unit[1-9]*.R

# 
grep --no-filename "^library" *.R

# using sed to handle stuff inside of R scripts/general files
sed 's/;\n/g' # replace every instance of first thing with newline globally 

# controlling jobs on a unix machine
# how to query and look for particular types of jobs (given by 'top')
ps -o #o flag: you can tell what columns you want to outpu
ps -o pid,pcpu,pmem,user,cmd
ps -o start_time --sort=start_time -C R # get R jobs started recently.

# xargs: pass arguments, not stdin to the function put right after it.


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# Discussion
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