useful-bash-commands.sh

ps -daf # show me all the processes and all the info

ps aux # show me processes as well, but more organized

lsof -i :<port> # get PID and other info of process running on port

# Below is an example of some things you can do with gawk/awk (gawk on mac). Read man for more detail.
some_command | gawk/awk '{variable = gensub(/<your regex>/,"\\1","g",$1); if(!d[ip]) { print variable; d[ip]=1; fflush(stdout)}'
#another awk example that I don't fully understand, but keeping it to look into later
some_command | awk '$1>1024 {print ":" $0; fflush()}'


#tcp dump with conditions & some helpful options
tcpdump -nn -q ip -l and 'dst port 8200 or dst port 8299 or dst port 80 or dst port 443'

# use the output of a command as an input to another with xargs
some_command | xargs some_command
# use the output of a command as an input to another with xargs, and only use the first column/output
some_command | xargs -n1 some_command




du -H # what's gunking up the current folder path

df # what's gunking up file system

sudo netstat -tulpn | grep LISTEN # What's listening -t == tcp, -u == udp, -l show listening, -p show PID, -n Don't resolve names

sudo journalctl -u service-name.service # see log output from service --since and --until can be used for dates
sudo journalctl -xefu service-name

lsblk # List blocks

# https://access.redhat.com/solutions/5540131
sudo growpart <disc> 1 # grows a partition (in this case 1) to fill out the rest of the disk
rpm -qa| grep -i growpart # Verify growpart package is installed, If not then install
yum install cloud-utils-growpart -y
# Verify the partition table using the below command before running growpart
parted <disc> u s p

lvextend +100%PVS <logical volume path> <physical volume path>

sudo service <service> restart

systemctl service restart
[ -z "$PROFILE" ] && echo "var exists" # check for variable
[ -z "$FILE" ] && echo "var exists" # check for file
[ -z "$DIR" ] && echo "var exists" # check for dir
arr=["a","b","c"]; if [[ "${arr[@]}" =~ "${DIR}," ]]; then echo "$DIR is in array"; fi # check that value is in array

# write multiple lines to a file
cat > ./file_name.ext <<EOL
file content
more content
EOL

# CLI input
while test $# -gt 0; do
  case "$1" in
    --var|-v)
      shift
      VAR=$1
      shift
      ;;
    *)
      echo "$1 is not a recognized flag!"
      usage
      exit 1;
      ;;
  esac
done
IFS=',' read -r -a array <<< "$string" # split string
IFS=$'\n' read -rd '' -a ids <<< "$string" # split string new line

#loop through array
for val in "${arr[@]}";
do
  echo $val
done



#function call
func () {
  echo "Arg 1: $1"
}
func "first argument"

ENV_VAR=$FENV_VAR envsubst < template.json > outfile.json #substitute values in a file

trap 'printf "\n"' DEBUG # Adds a blank line between any output on the screen.

export PS1="\n[\u@\h \W] $ " # change PS1 variable to include user & IP

# print with colors"
usage() {
  printf "usage:\\n\033[32m./run_change.sh -profile msysmc -region us-west-2 -service customer-alerts -cluster ecs51v-usw2-stg -new_cluster ecs52v-usw2-stg -build_project customer-alerts-api-deploy-stg\033[0m\\n"
}