logsave

Additional Notes

logsave runs a command and saves its output to a log file while simultaneously displaying it on the terminal. If the log file already exists, new output is appended. The tool also writes a timestamp header each time it runs.

It is similar to tee, but logsave is specifically designed for logging command output. It also responds to the SIGUSR1 signal by flushing and reopening the log file, which is useful for log rotation.

Syntax

logsave [options] logfile command [arguments...]

Parameters

• logfile: Path to the log file where output will be saved.
• command: The command to execute.
• arguments: Arguments to pass to the command.

Common Options

• -a, --append: Append to the log file instead of overwriting it.
• -s, --skip-if-exists: Skip logging if the log file already exists.
• --help: Display help and exit.

Examples

logsave build.log make

Run make, show output on the terminal, and save it to build.log.

logsave -a install.log make install

Append output to install.log instead of overwriting it.

logsave output.log ./deploy.sh

Log the output of a deployment script.

logsave -s status.log systemctl status nginx

Log the status command only if status.log does not already exist.

Practical Notes

• logsave is part of the util-linux package and is available on most Linux systems.
• Unlike script, logsave does not create a pseudo-terminal; it simply captures stdout and stderr.
• The timestamp format written by logsave is controlled by the LOGSAVE_TIMESTAMP environment variable.
• For simple logging, command | tee logfile is a more portable alternative.