Mastering the Linux logger Command to Write Custom Entries to System Logs

The logger utility (provided by the util-linux package) writes custom entries to the system log, which is typically stored in /var/log/syslog on Debian‑based distributions or /var/log/messages on RPM‑based systems.

Basic Usage

Write a simple message: logger "Welcome to OSTechNix" Verify the entry with:

tail -f /var/log/syslog

Quoting and Multiple Lines

Wrap the message in single or double quotes to preserve spaces and special characters:

logger "Welcome to OSTechNix blog"
logger 'Howdy, Welcome to OSTechNix blog'

Including the Process ID

Use -i to prepend the logger process’s PID to each line:

logger -i "Message with PID"

Tagging Messages

By default the tag is the current user name. Override it with -t (optionally combined with -i):

logger -i -t mytag "Tagged message"

Logging From a File

Write the contents of a file to the log with -f. Empty lines can be omitted with -e:

# Create a test file
 echo "This is a test file" > file.txt
# Log the file contents
 logger -f file.txt
# Omit empty lines
 logger -e -f file.txt

Setting Priority

Specify a syslog priority using --priority (or -p for short). The default is user.notice:

logger "Important notice" --priority user.warning

Sending to a Remote Syslog Server

Forward messages to a remote syslog daemon with --server (or -n) and --port (or -p). The standard syslog port is 514:

logger "Remote test" --server remote-host.example.com --port 514
logger "Remote test" -n remote-host.example.com -p 514

Limiting Message Size

Control the maximum length of a log entry with --size. The built‑in default is 1 KiB. Example truncates a long string to 5 bytes: logger --size 5 abcdefghijklmnopqrswxyz Check the truncated output with tail -f /var/log/syslog.

Reference

All options are documented in the manual page:

man logger