Bash Command

1. cut, rev, uniq, sort

cat 111 | egrep -o "Deleted: /.*/[0-9]{8}" | rev | cut -d "/" -f2- | rev | uniq -c | sort -nr


2. egrep all number and sum up

cat 111 | egrep -o "\[[0-9]+\] bytes" | egrep -o "[0-9]+" | awk '{sum+=$1} END {print sum}'

3. sh bash.sh  parameters

$@ means any parameters you passed to the script

4. strace all system call logs of a specific bash command

   strace -fvo /home/insights/insights/hive/tt3 -e\!futex -s 8192 bash ./hv

grep " open(" tt3|grep -v ENOENT|grep -v WR|awk -F\" '{print $2}'|sort -u | sed 's/home\/insights/xxx/g'|sed 's/xxx\/insights/yyy/g' | sed 's/yyy-etl-0.3.9-bin/yyy-etl-1.60-cdh4-bin/g' > files.7

5. For BSD or GNU grep you can use -B num to set how many lines before the match and -A num for the number of lines after the match.

grep -B 3 -A 2 foo README.txt

If you want the same amount of lines before and after you can use -C num.

grep -C 3 foo README.txt



6.  Copy or paste to clipboard (for mac OS)


pbcopy

pbpaste








7. Print number of fields of each line delimited by '\t'

cat kfb_topic_task1_v4 | awk -F'\t' '{print NF}' 

8. redirection doesn't work for sudo
e.g. this won't work if you don't have permission to write the file since sudo won't apply on the redirection

sudo echo 1 > /proc/sys/vm/overcommit_memory'

To solve this :

sudo sh -c 'echo 1 > /proc/sys/vm/overcommit_memory'

You can also do this easily by : echo 1 | sudo tee /proc/sys/vm/overcommit_memory