crond

cron daemon for job scheduling

TLDR

Start daemon in background
$ crond
Start daemon in foreground
$ crond -n
Send output to syslog
$ crond -s
Accept custom crontabs (override limitations)
$ crond -p
Inherit PATH from environment
$ crond -P
Enable clustering support
$ crond -c

SYNOPSIS

crond [OPTIONS]

DESCRIPTION

crond is a daemon that executes scheduled commands from crontab files. It starts automatically at boot and checks crontab files for jobs that need to run each minute. It monitors /var/spool/cron/ (user crontabs), /etc/crontab (system crontab), and /etc/cron.d/ (system cronjobs). The flags below describe the cronie implementation, the crond shipped on most modern distributions; BusyBox and dcron provide their own crond with overlapping but not identical options.

PARAMETERS

-n

Run in foreground (useful for init systems)
-s
Send job output to syslog instead of email
-m COMMAND
Specify custom mail command or disable with "off"
-p
Override default limitations and accept custom crontabs
-P
Inherit PATH from environment instead of setting default
-c
Enable clustering support for shared crontabs
-h
Display help information
-V
Display version number

CONFIGURATION

/etc/crontab

System-wide crontab file monitored by crond.
/etc/cron.d/
Directory containing additional system crontab files.
/var/spool/cron/
Directory containing user-specific crontab files (one per user). Debian's cron uses /var/spool/cron/crontabs/ instead.

INSTALL

sudo apt install cronie
sudo dnf install cronie
sudo pacman -S cronie
sudo apk add cronie
sudo zypper install cronie
nix profile install nixpkgs#cronie

CAVEATS

Job output is mailed to the crontab owner unless redirected to syslog with -s or a custom mail command. Crontab files must be regular files, not executable, and writable only by the owner. Local time changes (like DST) under three hours receive special handling.

HISTORY

crond is the daemon component of cron, a standard Unix job scheduler that has been in use since Version 7 Unix. Modern implementations include Vixie cron and cronie.

SEE ALSO

crontab(1), crontab(5), anacron(8)

RESOURCES

Source code