Skip to content

Instantly share code, notes, and snippets.

@dserodio dserodio/history.sh
Last active Sep 13, 2019

Embed
What would you like to do?
Misc bash snippets
# Show timestamp for history output
export HISTTIMEFORMAT="%d/%m/%y %T "
# use /etc/tcp to make TCP connections in plain bash
exec 3<>/dev/tcp/www.google.com/80
echo -e "GET / HTTP/1.1\r\nhost: http://www.google.com\r\nConnection: close\r\n\r\n" >&3
cat <&3
#!/bin/sh
# POSIX
# Found at http://mywiki.wooledge.org/BashFAQ/035#Manual_loop
# Reset all variables that might be set
file=
verbose=0 # Variables to be evaluated as shell arithmetic should be initialized to a default or validated beforehand.
while :; do
case $1 in
-h|-\?|--help) # Call a "show_help" function to display a synopsis, then exit.
show_help
exit
;;
-f|--file) # Takes an option argument, ensuring it has been specified.
if [ -n "$2" ]; then
file=$2
shift
else
printf 'ERROR: "--file" requires a non-empty option argument.\n' >&2
exit 1
fi
;;
--file=?*)
file=${1#*=} # Delete everything up to "=" and assign the remainder.
;;
--file=) # Handle the case of an empty --file=
printf 'ERROR: "--file" requires a non-empty option argument.\n' >&2
exit 1
;;
-v|--verbose)
verbose=$((verbose + 1)) # Each -v argument adds 1 to verbosity.
;;
--) # End of all options.
shift
break
;;
-?*)
printf 'WARN: Unknown option (ignored): %s\n' "$1" >&2
;;
*) # Default case: If no more options then break out of the loop.
break
esac
shift
done
# if --file was provided, open it for writing, else duplicate stdout
if [ -n "$file" ]; then
exec 3> "$file"
else
exec 3>&1
fi
# Rest of the program here.
# If there are input files (for example) that follow the options, they
# will remain in the "$@" positional parameters.
Sign up for free to join this conversation on GitHub. Already have an account? Sign in to comment
You can’t perform that action at this time.