Scenario

Multiple applications write logs under /var/log, and you need to quickly check if any recent errors have been recorded.

Task

Search recursively under /var/log for all files ending with .log, print every line that contains the text ERROR, ensure the output includes both the filename and the matching line, and save the results to /home/devops/error_logs.txt.

Example

# Before (multiple log files scattered across directories)
/var/log/apache2/error.log
/var/log/apache2/access.log
/var/log/application.log
/var/log/mysql/error.log
/var/log/syslog

# After (ERROR lines found and saved to /home/devops/error_logs.txt)
/var/log/apache2/error.log:ERROR: Connection timeout to database server
/var/log/application.log:ERROR: Unable to write to cache directory
/var/log/mysql/error.log:ERROR: InnoDB: Cannot allocate memory for buffer pool
/var/log/syslog:ERROR: Disk quota exceeded for user appuser

Step 1: Search recursively for ERROR in all .log files under /var/log.

grep -r "ERROR" /var/log --include="*.log" 2>/dev/null

Step 2: Save the output to the required file.

grep -r "ERROR" /var/log --include="*.log" 2>/dev/null > /home/devops/error_logs.txt