#Linux

bash

LS_COLORS=$LS_COLORS:'di=0;35:' ; export LS_COLORS; ls
export LS_OPTIONS='--color=auto'
#eval "$(dircolors -b)"
alias ls='ls $LS_OPTIONS'




# tmux 


alias tmux="TERM=screen-256color-bce tmux"

command

$ cd - 
switch to the previous directory

$ pv access.log | gzip > access.log.gz
611MB 0:00:11 [58.3MB/s] [=>      ] 15% ETA 0:00:59

$ sudo !!
Rerun the previous command as root.



Ctrl-R
searches the command history. 

ALT-. (ESC+. in some terminals) copies last used argument (super-useful)

CTRL-W deletes word

CTRL-L clear terminal (like clear command but faster)

ALT-B (ESC+B in some terminals) move backward a word

ALT-F (ESC+F in some terminals) move forward a word

CTRL-E jump to EOL

CTRL-A jump to BOL and CTRL-K delete the line



for item in items; do `echo` ricky-action; done
add `echo` before committing like `rm $files` (varibale expansion[preceed with $], or glob[* ?])

set -x
check the flow of script

$ watch 
watch tail logfile1 logfile2


$ grep -l : only matched filename
       -L : only not matched filename
       -n : show the number of line
       -w : not substring

$ find . -type l 
find symbolic link


$ find . -name * | xargs grep 
combination with gerp and find



combination
sudo find . -name  "*.py" | xargs grep -wsl fairseq --color | awk 'BEGIN{FS="/";OFS="/"} {print $2,$3}' | uniq -d


$ nohup:
- nohup my_command > my.log 2>&1 &
- echo $! > save_pid.txt



# shell instance PID
echo "$$"

# find the process by giving PID
ps -p <PID>


$ sed:
- sed -n '{200,250p}' article_tagging_min.py


$ lsof | grep nohup.out


$ awk:

combin=$(IFS='|' ; echo "${data[*]}")
pattern="/(${combin})($|,)/"
echo $pattern
awk "$pattern" $INPUT > $OUTPUT


# check ICMP (Ping) enabled(0), disabled(1)
cat /proc/sys/net/ipv4/icmp_echo_ignore_all


# dig xxx ANY: all record 
# dig -x: query PTR(IP -> domain name)



# sudo -i : become root and use `root` shell (path / env)
# (sudo) su - become root and use `root` shell but not in /home/root


su cindy: become cindy but use harry shell
su - cindy: become cindy and use cindy shell