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Reload shell without exit

exec $SHELL -l

Close shell keeping all subprocess running

disown -a && exit

Exit without saving shell history

kill -9 $$
unset HISTFILE && exit

Perform a branching conditional

true && echo success
false || echo failed

Pipe stdout and stderr to separate commands

some_command > >(/bin/cmd_for_stdout) 2> >(/bin/cmd_for_stderr)

Redirect stdout and stderr each to separate files and print both to the screen

(some_command 2>&1 1>&3 | tee errorlog ) 3>&1 1>&2 | tee stdoutlog

List of commands you use most often

history | \
awk '{CMD[$2]++;count++;}END { for (a in CMD)print CMD[a] " " CMD[a]/count*100 "% " a;}' | \
grep -v "./" | \
column -c3 -s " " -t | \
sort -nr | nl |  head -n 20

Sterilize bash history

function sterile() {
 
  history | awk '$2 != "history" { $1=""; print $0 }' | egrep -vi "\
curl\b+.*(-E|--cert)\b+.*\b*|\
curl\b+.*--pass\b+.*\b*|\
curl\b+.*(-U|--proxy-user).*:.*\b*|\
curl\b+.*(-u|--user).*:.*\b*
.*(-H|--header).*(token|auth.*)\b+.*|\
wget\b+.*--.*password\b+.*\b*|\
http.?://.+:.+@.*\
" > $HOME/histbuff; history -r $HOME/histbuff;
 
}
 
export PROMPT_COMMAND="sterile"

Look also: A naive utility to censor credentials in command history.

Quickly backup a file

cp filename{,.orig}

Empty a file (truncate to 0 size)

>filename

Delete all files in a folder that don't match a certain file extension

rm !(*.foo|*.bar|*.baz)

Pass multi-line string to a file

# cat  >filename ... - overwrite the file
# cat >>filename ... - append to a file
cat > filename << __EOF__
data data data
__EOF__

Edit a file on a remote host using vim

vim scp://user@host//etc/fstab

Create a directory and change into it at the same time

mkd() { mkdir -p "$@" && cd "$@"; }

Convert uppercase files to lowercase files

rename 'y/A-Z/a-z/' *

Print a row of characters across the terminal

printf "%`tput cols`s" | tr ' ' '#'

Show shell history without line numbers

history | cut -c 8-
fc -l -n 1 | sed 's/^\s*//'

Run command(s) after exit session

cat > /etc/profile << __EOF__
_after_logout() {
 
  username=$(whoami)
 
  for _pid in $(ps afx | grep sshd | grep "$username" | awk '{print $1}') ; do
 
    kill -9 $_pid
 
  done
 
}
trap _after_logout EXIT
__EOF__

Generate a sequence of numbers

for ((i=1; i<=10; i+=2)) ; do echo $i ; done
# alternative: seq 1 2 10
 
for ((i=5; i<=10; ++i)) ; do printf '%02d\n' $i ; done
# alternative: seq -w 5 10
 
for i in {1..10} ; do echo $i ; done

Simple Bash filewatching

unset MAIL; export MAILCHECK=1; export MAILPATH='$FILE_TO_WATCH?$MESSAGE'

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