What does this cron to systemd converter produce?

It generates OnCalendar schedules and starter .timer/.service unit templates from cron expressions, including comments that map back to each source line.

Does it support cron macros such as @daily?

Yes. Common macros are normalized into equivalent standard cron fields before conversion.

Can I convert multiple cron lines at once?

Yes. Paste multiple expressions and the converter outputs one timer/service template pair per line.

Why are some expressions flagged as unsupported?

Quartz-only tokens like L, W, #, and ? are not safely equivalent in systemd OnCalendar format, so the converter blocks them with clear diagnostics.

Cron to Systemd Timer Converter

Convert cron schedule expressions into equivalent systemd .timer configurations with generated OnCalendar values, unit templates, and migration diagnostics for unsupported syntax.

Convert cron schedules into systemd OnCalendar values and starter .timer/.service unit templates. This helps migrate scheduled tasks from crontab to systemd with fewer manual mapping mistakes.

Cron Input

Systemd Output

# Source line 2: */15 * * * * /usr/local/bin/job-a.sh
# Normalized cron: */15 * * * *
# OnCalendar: *-*-* *:*/15:00

# 2-cron-job.timer
[Unit]
Description=cron-job-line-2 timer

[Timer]
OnCalendar=*-*-* *:*/15:00
Persistent=true
AccuracySec=1s

[Install]
WantedBy=timers.target

# 2-cron-job.service
[Unit]
Description=cron-job-line-2 service

[Service]
Type=oneshot
ExecStart=/usr/bin/env bash -lc 'echo "Replace cron-job-line-2 command"'

# Source line 3: 0 2 * * 1-5
# Normalized cron: 0 2 * * 1-5
# OnCalendar: Mon..Fri *-*-* 2:0:00

# 3-cron-job.timer
[Unit]
Description=cron-job-line-3 timer

[Timer]
OnCalendar=Mon..Fri *-*-* 2:0:00
Persistent=true
AccuracySec=1s

[Install]
WantedBy=timers.target

# 3-cron-job.service
[Unit]
Description=cron-job-line-3 service

[Service]
Type=oneshot
ExecStart=/usr/bin/env bash -lc 'echo "Replace cron-job-line-3 command"'

# Source line 4: @daily
# Normalized cron: 0 0 * * *
# OnCalendar: *-*-* 0:0:00

# 4-cron-job.timer
[Unit]
Description=cron-job-line-4 timer

[Timer]
OnCalendar=*-*-* 0:0:00
Persistent=true
AccuracySec=1s

[Install]
WantedBy=timers.target

# 4-cron-job.service
[Unit]
Description=cron-job-line-4 service

[Service]
Type=oneshot
ExecStart=/usr/bin/env bash -lc 'echo "Replace cron-job-line-4 command"'

# Source line 5: 30 4 1 * *
# Normalized cron: 30 4 1 * *
# OnCalendar: *-*-1 4:30:00

# 5-cron-job.timer
[Unit]
Description=cron-job-line-5 timer

[Timer]
OnCalendar=*-*-1 4:30:00
Persistent=true
AccuracySec=1s

[Install]
WantedBy=timers.target

# 5-cron-job.service
[Unit]
Description=cron-job-line-5 service

[Service]
Type=oneshot
ExecStart=/usr/bin/env bash -lc 'echo "Replace cron-job-line-5 command"'

Total Expressions

Converted

Warnings

Errors

Converted 4/4 expressions.

Conversion Diagnostics (1)

Line 2Ignored trailing command text after cron fields when generating systemd units.

Features

Cron to OnCalendar Conversion

Convert standard 5-field cron expressions into systemd OnCalendar schedules line by line.

Timer and Service Unit Output

Generate ready-to-edit .timer and .service templates with clear source mapping comments.

Macro Support

Translates @daily, @hourly, @weekly, and related cron macros into equivalent schedules.

Syntax Risk Diagnostics

Flags unsupported Quartz-only syntax and warns when command text is ignored in conversion.

Use Cases

Migrating from crontab to systemd

Move legacy cron jobs into service-managed systemd timers with clearer unit-based configuration.

Infrastructure Standardization

Normalize scheduling patterns across servers that rely on systemd instead of per-user crontabs.

DevOps Review and Auditing

Review OnCalendar schedules in plain format and keep timer definitions version-controlled.

Container and VM Boot Persistence

Use Persistent=true timer templates to handle missed runs after downtime or reboot windows.

Documentation and Knowledge Transfer

Generate readable unit file stubs that serve as living documentation for scheduled tasks, making handoffs between teams easier.

Multi-Server Deployment Validation

Confirm that converted OnCalendar expressions behave identically across servers with different timezones or locale settings before rolling out.

About Cron to Systemd Timer Converter

Why convert cron to systemd timers

Systemd timers integrate scheduling with service management, centralized logs, dependencies, and startup behavior. They are often easier to audit and manage than scattered user-level crontab entries.

What this converter outputs

For each cron line, the tool produces an OnCalendar value plus starter .timer and .service unit blocks. It also highlights unsupported syntax so you can fix expressions before deployment.

Key differences between cron and systemd timers

Unlike cron, systemd timers support monotonic clocks (OnBootSec, OnUnitActiveSec) for relative scheduling, dependency ordering via After= and Requires=, and automatic logging through journald. These features make timers more predictable in containerized and cloud environments.

Persistent timers and missed runs

Setting Persistent=true in a timer unit causes systemd to run the service immediately if the last scheduled activation was missed, such as after a reboot or downtime window. This replaces the need for anacron-style wrappers that cron setups often require.

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Frequently Asked Questions

Does this converter support standard 5-field cron syntax?

Yes. It supports minute, hour, day-of-month, month, and day-of-week cron expressions, including ranges, lists, and step values.

Can I paste full crontab lines with commands?

Yes. The converter reads the first 5 scheduling fields and warns that trailing command text is ignored in generated unit templates.

Are cron macros like @daily supported?

Yes. Common macros such as @hourly, @daily, @weekly, @monthly, and @yearly are normalized before conversion.

What syntax is not supported?

Quartz-specific tokens like L, W, #, and ? are flagged as unsupported to avoid unsafe or incorrect systemd mappings.

Is this tool private and free?

Yes. Conversion runs in your browser, requires no signup, and is 100% free to use.

How do I activate the generated systemd timer after conversion?

Copy the generated .timer and .service unit files to /etc/systemd/system/, then run systemctl daemon-reload and systemctl enable --now your-timer.timer to activate the schedule.

Does the converter handle step values like */5 in cron expressions?

Yes. Step values such as */5 * * * * are translated into the equivalent OnCalendar interval notation in the generated systemd timer unit.