Writing into output file from prompt in bash

Question

I've been working on some script, and took a simple short snapshot out and wanted to share to see if someone could help out,. I am basically using prompt to execute my script. First prompt will ask me if I want to continue, which works fine, second prompt will ask me if I want to write my output into txt file, which works fine too. However my question is if there's a way to tell the script somehow to write the output into txt file when I hit Yes, but more likely if there's a way to do it without duplicating my commands? I know I could just write all commands into the output prompt, and depending if I hit yes or no it would write or skip writing.

#!/bin/bash

# Disclaimer
read -p "[Y] for Yes or [N] for GTFO: " prompt
if [[ $prompt == "y" ||  $prompt == "" ]]
then

# Output save
read -p "[Y] to save output to txt [N] don't save: " prompt
if [[ $prompt == "y" ||  $prompt == "" ]]
then
    touch /root/Desktop info.txt
    ifconfig >> /root/Desktop info.txt

fi
printf "\n"
    printf "Executing script, and will scan the system for information \n"
sleep 1.4
printf "\n"

# Will Check for IP
printf "IP Addresses: \n"
ifconfig

else
    printf "\n"
    printf "Exiting, Bye \n"

fi

William Pursell · Accepted Answer · 2017-11-02 17:10:57Z

1

If you want to record the output of the script to a file only when the user requests it, you could do:

if [[ $prompt == "y" ||  $prompt == "" ]]
then
    trap 'rm $fifo' 0 
    fifo=$(mktemp)
    rm $fifo
    mkfifo $fifo
    tee output-of-script < $fifo &
    exec > $fifo  # All output of any command run will now go to the fifo,
                  # which will be read by tee
fi

It's probably cleaner to allow the user to specify an output file name rather than hardcoding the file 'output-of-script', and I would strongly advise against prompting; it is much cleaner to specify this sort of thing as a command line argument.

Of course, if you don't want to duplicate output to the current stdout and the file, this is much simpler:

if ...; then exec > output-file; fi

will cause the output of all subsequent commands to be written to output-file

Also, if you're using bash, running the tee can be simpler, too:

if ...; then exec > >(tee output-file); fi

edited Nov 2, 2017 at 17:10

answered Nov 2, 2017 at 17:05

William Pursell

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1 Comment

P_n Over a year ago

thats great! Thank you so much for the help! I like this

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