Answer:

Suppose you want to grep a specific code from files with a specific file extension, you can try

# grep -r --include \*.php 'error_log(' .

Answer:

To list the dot underscore files in a Mac directory, you can use:

# find . -name '._*' -exec ls {} \;

To remove them, you can try:

# find . -name '._*' -exec rm -v {} \;

Answer:

To do so, use the command:

#jps -mlvV

Sometimes, when you've removed files without using the git rm and git will warn you the message "Changed but not updated.."

To fix this, you can use the command

# git ls-files --deleted -z | xargs -0 git rm

Answer:

To trap your script before exit, you can use the trap in bash, e.g.

#!/bin/bash

set -eu

function bye {
  echo "Good bye"
}

trap bye EXIT
sleep 1000 
# Quit the script by pressing Ctrl+C

Answer:

If you want to tail a remote file over ssh, you can use

# ssh -t remote-server "tail -f /var/log/log.txt"

Answer:

You should always start your bash shell script with the line set -eu

The meaning is:

1. -e: cause the script to exit if an error
2. -u: cause the script to exit if any variable is not set

Answer:

To clear your terminal's shell buffer in Mac OS X, you can use COMMAND + K

Answer:

You can list all system's currently installed locales via the command: locale -a

Answer:

If you have a list of IPs and need to resolve to the hostname(via reverse DNS lookup), you can use the following command:

cat ip_addresses.txt | xargs -n 1 -P 100  -i dig -x {} +short