Developer tools · Crontab generator
Cron job works in the shell but not in crontab: PATH and environment
· How it works
cron validation developer-workflow
Cron does not read your .bashrc, does not use bash, and starts with a PATH of a few directories. This post explains the environment a cron job actually gets and the three lines that fix most failures.
It works when I run it — the same script does nothing from crontab and there is no error anywhere you looked
A green result for `0 2 * * *` proves that ToolAcre recognizes a daily 02:00 schedule. It does not prove that a script exists, can be executed, finds its dependencies or writes its output. The parser receives only five fields, so a later command failure does not contradict schedule validation.
This distinction narrows troubleshooting. First confirm that the intended dates and times appear in the description and preview. Then move to the machine that will execute the line and examine command behavior there. Mixing both questions encourages edits to a correct expression while the actual defect sits beyond the parser’s input.
The generator can validate timing while a separately executed command still fails
The workbook asserted a particular set of environment variables and login-file behavior. None of that is implemented or tested in this repository. ToolAcre neither launches a cron daemon nor captures an execution environment, so it cannot say which variables a specific host, package or administrator supplies.
Record the target implementation and inspect its documentation or a harmless diagnostic run. The generator’s only environment-dependent input is the time zone chosen for preview. That zone affects displayed candidate instants; it does not simulate process variables, home directories, credentials or startup files for a future command.
Environment variables supplied by a cron daemon are outside repository evidence
No shell receives the expression inside ToolAcre. `parseCron` tokenizes whitespace-separated schedule fields, expands their tiny grammar and stops. Even the “Copy crontab line” action appends `/usr/local/bin/your-command` as an obvious placeholder. It does not select a shell or test shell syntax.
Therefore arrays, conditionals, substitutions and shebang behavior are deliberately absent from this article’s claims. A command can be valid for one shell and invalid for another while its five timing fields remain identical. Check the actual execution contract separately instead of treating a human-readable schedule as command certification.
The command shell is not parsed or selected by this tool
Assignment lines such as `PATH=...` or `SHELL=...` are not accepted by the expression box. They have fewer than five timing fields and fail validation. This is correct for the route’s narrow purpose: its parser is an expression parser, not a complete crontab-file parser.
Do not paste configuration text until one line happens to pass. Keep schedule construction isolated, then assemble the surrounding file according to the target’s own grammar. This avoids a dangerous category error in which a tool’s refusal is interpreted as evidence that an environment feature is universally invalid.
Crontab assignment syntax is outside the five-field input
Absolute and relative path behavior belongs to the process that eventually runs the command. ToolAcre does not call `chdir`, inspect a filesystem or resolve executables. Its source list contains calendar arithmetic and browser controls, not process-spawning code. A copied expression carries no working-directory information.
A deployment review should identify the executable, data paths and account independently. Those checks may reveal a missing file even when every previewed time is correct. The schedule can be reused beside different commands, which is precisely why successful parsing cannot imply that any one command is reachable.
Paths and working directories remain deployment concerns
Use a harmless, observable command chosen for the target system after validating the timing fragment. Confirm that it runs under the intended account and environment, then replace it only after those conditions are understood. ToolAcre contributes the expression and expected calendar times; host-side evidence contributes execution behavior.
For example, build `30 2 * * *` and verify that the description says 02:30 every day in the selected zone. Copy only those fields into deployment work. The article does not prescribe a Python path, virtual environment or redirect because no corresponding implementation exists in the repository to substantiate one.
Worked boundary: validate the schedule, then test a harmless command in the target environment
Container schedulers, systemd timers and cloud products can expose different environment and command models. They may also use grammars that merely resemble cron. This route does not detect those platforms, read their unit files or translate their settings, so cross-platform execution advice would be speculation.
If the destination rejects a ToolAcre-valid expression, compare its field count and supported operators before changing values. If it accepts the expression but the task fails, leave the schedule alone while investigating the destination’s command contract. That fork keeps grammar debugging separate from runtime debugging.
Other schedulers and containers are not modeled
A cron line combines two systems: a calendar expression and an executable action. ToolAcre owns the first half only. It validates ranges, lists, steps, aliases and day-field semantics, then describes and previews them. It makes no execution guarantee and should not be used as evidence that a command succeeded.
Treat the generator’s output as a checked schedule fragment. Preserve the chosen zone beside it, test the action where it will run and collect observable output there. This disciplined boundary is more useful than broad advice about a hypothetical daemon because it tells you exactly which green signal you have earned.