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我有一个 crontab 看起来像
0 0 * * * pg_dump DB_NAME > /path/to/dumps/`date +%Y%m%d`.dmp
当我手动运行它时它工作正常，但当 cron 运行它时就不行了。挖掘日志后，我看到了
Dec 12 00:00:01 localhost crond[17638]: (postgres) CMD (pg_dump DB_NAME > /path/to/dumps/`date +)
看起来像是百分号的问题，但是 man 页面甚至根本不包含百分号，所以我认为它们没问题。
最佳答案
你必须用反斜杠转义百分号:
0 0 * * * pg_dump DB_NAME > /path/to/dumps/`date +\%Y\%m\%d`.dmp
来自 man 5 crontab:
The ‘‘sixth’’ field (the rest of the line) specifies the command to be run. The entire command portion of the line, up to a newline or % character, will be executed by /bin/sh or by the shell specified in the SHELL variable of the crontab file. Percent-signs (%) in the command, unless escaped with backslash (\), will be changed into newline characters, and all data after the first % will be sent to the command as standard input. There is no way to split a single command line onto multiple lines, like the shell’s trailing "\".
关于linux - cron 执行的命令是否有特殊限制？，我们在Stack Overflow上找到一个类似的问题： https://stackoverflow.com/questions/363049/