ts

Add timestamps to command output

$ [command] | ts

$ [command] | ts -i

$ [command] | ts -m

$ [command] | ts -u

$ [command] | ts -s

$ [command] | ts -i

$ [command] | ts '[%Y-%m-%d %H:%M:%S]'

$ [command] | ts -r

ts [-imsu] [-r] [format]

ts reads lines from standard input, prepends a timestamp to each line, and writes to standard output. It is part of the moreutils package and is useful for logging, debugging, and monitoring command output over time.
The default timestamp format is "%b %d %H:%M:%S" (e.g., "Jan 22 14:30:45"). Custom formats use strftime conversion specifications. Extended specifiers %.S, %.s, and %.T provide subsecond resolution.
The -s option shows cumulative time since ts started, useful for measuring total elapsed time. The -i option shows time between lines, helpful for identifying slow operations in pipelines.
The -r option converts existing timestamps in the input to human-readable relative times, supporting many common timestamp formats.

-i

Show incremental time elapsed since last timestamp

Show time elapsed since program start

Include milliseconds in timestamps

Use UTC time instead of local time

Convert existing timestamps to relative times (e.g., "15m5s ago")

Custom strftime format (default: "%b %d %H:%M:%S")

Monitor log file with timestamps

$ tail -f /var/log/syslog | ts

$ make 2>&1 | ts -i '[%H:%M:%S]'

$ ./long_script.sh | ts -s '%.T'

ts requires the moreutils package, which may not be installed by default. The command buffers output, which can cause slight delays when used with slowly producing commands. Timestamps reflect when ts receives each line, not when the original command produced it.

ts was written by Joey Hess as part of moreutils, a collection of Unix utilities. Moreutils was first released around 2006 to provide additional tools that complement the standard coreutils, filling gaps in common command-line workflows.

date(1), strftime(3), sponge(1), chronic(1)