CODEWITHSUNDEEP
shellloggingexecstdout
Assa Yeroslaviz
Assa Yeroslaviz

Reputation: 764

How to terminate the logging process inside a shell script withput stopping the script?

I am working with a shell script to run my analyses. To make sure, I can confirm the correct commands were executed, I am writing the complete STDOUT/STDERR output into a file

My script looks like that:

#!/bin/bash

# Here are some pliminary stuff

echo " this goes still to the STDOUT to control the begining of the script"

#### execute all output to log files
# to set a log file, where all echo command will be redirected into.
touch $projectName\_logfile.txt # creating the log file
exec &> $projectName\_logfile.txt # direct all output to the log file

echo "1. These steps should be written to the log file"

# exit 
# exec >&-

echo "2. 2. these steps should be written to the STDOUT again!"

# The script should be able to continue here ...

As you can see I have tried both using the exit command as well as closing the file descriptor using exec again. But both have failed.

I would appreciate your help to understand how to close the connection to the log file and redirect everything back to the STDOUT/STDERR.

thanks Assa

Upvotes: 2

Views: 2520

Answers (1)

Kubator
Kubator

Reputation: 1383

I would rather consider this way:

echo "to out 1"
{
  echo "to log 1"
  echo "to log 2"
} &> ./_logfile.txt 
echo "to out 2"

Anyway if You still need to use Your approach then You need to save original file descriptors:

exec 3<&1 # save original stdout to 3
exec 4<&2 # save original stderr to 4

And then restore:

exec 1>&3 # restore original stdout
exec 2>&4 # restore original stderr

Your example:

#!/bin/env bash

echo " this goes still to the STDOUT to control the begining of the script"

touch ./_logfile.txt # touch the log file
exec 3<&1 # save original stdout to 3
exec 4<&2 # save original stderr to 4
exec &> ./_logfile.txt # direct all out and err to the log file

echo "1. These steps should be written to the log file"

exec 1>&3 # restore original stdout
exec 2>&4 # restore original stderr

echo "2. 2. these steps should be written to the STDOUT again!"

# The script should be able to continue here ...

Upvotes: 3

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