Collecting Data from a UNIX Program with Bash Redirecting
I am trying to write a script that outputs a CSV file (user specified) from the temperature value given by the acpi program. Each data record is appended to the CSV file every second (for now).
I have two problems to be solved in my script:
To fix errors in the script (like a file access error on line 14) and allow the user to specify a time delay.
Here's the bash script:
#!/bin/bash
# This script monitors the CPU temperature (in degrees C) over time, and
# records the data to a CSV file.
# Written by Ben Cottrell
function start_log()
{
touch "$output_csv"
if hash acpi 2>/dev/null; then
echo -e "time,temperature\n" > "$output_csv"
while (true); do
sleep 1
echo -e "$(date +%T),$(acpi -t | awk '{print $4}')\n" >> "$output_csv"
done
else
echo "Error: acpi is not installed. Please execute \"sudo apt-get install acpi, before running this script.\""
fi
}
if [ "$1" ]; then
local output_csv = $1
start_log
else
echo -e "Error: No filename specified.\n"
fi
echo -e "\n"
source to share
Errors with worst-case errors and idiom violations are rewritten here.
#!/bin/bash
function start_log()
{
local output_csv=$1
local delay=$2
if hash acpi 2>/dev/null; then
echo "time,temperature" > "$output_csv"
while true; do
sleep "$delay"
echo "$(date +%T),$(acpi -t | awk '{print $4}')"
done >>"$output_csv"
else
cat <<________error >&2
$0: Error: acpi is not installed.
Please execute \"sudo apt-get install acpi\" before running this script.
________error
exit 2
fi
}
delay=1 # default to 1 sec delay
while true; do
case $1 in
-t) shift; delay=$1; shift;; # Maybe validate the value of $delay
-*) echo "$0: Unknown option: '$1'" >&2; exit 1;;
*) break;;
esac
done
if [ "$1" ]; then
start_log "$1" "$delay"
else
echo "$0: Error: No filename specified." >&2
exit 1
fi
Including the program name in error messages is useful when it is called from another script, which might be called from another script, etc.
Note that the redirection is done only once, after the loop, and not repeatedly inside the main loop.
Notice also how the function gets its parameters from the caller, instead of pulling in global variables.
Handling parameter parsing is hardly more difficult than "doing it right" with getopts
simple handling.
source to share
Try it.
#!/bin/bash
# This script monitors the CPU temperature (in degrees C) over time, and
# records the data to a CSV file.
# Written by Ben Cottrell
function start_log()
{
touch "$output_csv"
read -p 'Enter the time interval for collecting data in seconds: ' t
if hash acpi 2>/dev/null; then
echo -e "time,temperature\n" > "$output_csv"
while (true); do
sleep $t
echo -e "$(date +%T),$(acpi -t | awk '{print $4}')\n" >> "$output_csv"
done
else
echo "Error: acpi is not installed. Please execute \"sudo apt-get install acpi, before running this script.\""
fi
}
if [ -n "$1" ]; then
local output_csv = $1
start_log
else
echo -e "Error: No filename specified.\n"
fi
echo -e "\n"
source to share