不確定是否執行 cron 作業

我有以下 cron 工作/etc/cron.d/backup：

*/1 * * * * backupbot /home/backupbot/bin/backup-script.sh

基本上，我希望backup-script.sh每分鐘執行一次（並且使用者備份機器人應該正在執行該作業）。

該/home/backupbot/bin/backup-script.sh文件歸backupbot所有（他擁有“x”權限）。該文件如下所示：

#!/bin/bash
set -e

{

BACKUP_DIR=/var/app/backups
STORAGE_ACCOUNT_URL=https://myserver/backups

BACKUP_FILE=$(ls $BACKUP_DIR -t | head -1)

if [ -z "$BACKUP_FILE" ]; then
   echo "There are no backups to synchronize"
   exit 0
fi

azcopy login --identity
azcopy copy $BACKUP_DIR/$BACKUP_FILE $STORAGE_ACCOUNT_URL/$BACKUP_FILE

} >/tmp/cron.backup-script.$$ 2>&1

通常，任何輸出都應登錄到/tmp/cron.backup-script.xxxx. 永遠不會創建這樣的文件。

Cron 注意到該作業的唯一證據是以下輸出systemctl status cron.service：

● cron.service - Regular background program processing daemon
  Loaded: loaded (/lib/systemd/system/cron.service; enabled; vendor preset: enabled)
  Active: active (running) since Tue 2021-04-13 09:59:08 UTC; 6h ago
    Docs: man:cron(8)
Main PID: 1086 (cron)
   Tasks: 1 (limit: 4915)
  CGroup: /system.slice/cron.service
          └─1086 /usr/sbin/cron -f

Apr 13 16:00:01 my-vm CRON[17201]: pam_unix(cron:session): session closed for user root
Apr 13 16:00:01 my-vm CRON[17198]: pam_unix(cron:session): session closed for user root
Apr 13 16:00:01 my-vm CRON[17199]: pam_unix(cron:session): session closed for user root
Apr 13 16:01:01 my-vm CRON[17402]: pam_unix(cron:session): session opened for user root by (uid=0)
Apr 13 16:01:01 my-vm CRON[17403]: (root) CMD ([ -f /etc/krb5.keytab ] && [ \( ! -f /etc/opt/omi/creds/omi.keytab \) -o \( /etc/krb5.keytab -nt /etc/opt/omi/creds/omi.keytab \) ] &&
Apr 13 16:01:01 my-vm CRON[17401]: pam_unix(cron:session): session opened for user backupbot by (uid=0)
Apr 13 16:01:01 my-vm CRON[17404]: (backupbot) CMD (/home/backupbot/bin/backup-script.sh)
Apr 13 16:01:01 my-vm CRON[17402]: pam_unix(cron:session): session closed for user root
Apr 13 16:01:01 my-vm CRON[17401]: (CRON) info (No MTA installed, discarding output)
Apr 13 16:01:01 my-vm CRON[17401]: pam_unix(cron:session): session closed for user backupbot

它提到了有關backupbot的會話。我該如何進一步調查？

根據評論，該腳本只能由所有者執行。即，它不可讀。這會阻止所有者執行腳本。

例子：

$ chmod 500 script
$ ls -l script
-r-x------ 1 myself myself 24 Apr 14 09:21 script
$ ./script
hello

$ chmod 100 script
$ ls -l script
---x------ 1 myself myself 24 Apr 14 09:21 script
$ ./script
/bin/bash: ./script: Permission denied

bash如果腳本文件不可讀，則shell 解釋器（以目前使用者身份執行）無法讀取它。

使腳本既可執行又可讀。

---

除了上述之外，考慮使用適當的雙引號變數擴展，並且不要解析輸出ls（它只是真正有用的看）。

您的腳本，已修改：

#!/bin/bash

backup_dir=/var/app/backups
storage_account_url=https://myserver/backups

{
   # Find most recently modified file in "$backup_dir".
   # Assumes that there are only files there, no subdirectories.

   set -- "$backup_dir"/*
   backup_file_path=$1
   shift

   for pathname do
       if [ "$pathname" -nt "$backup_file_path" ]; then
           backup_file_path=$pathname
       fi
   done
   
   if [ ! -e "$backup_file_path" ]; then
       echo 'There are no backups to synchronize'
       exit 1
   fi
   
   # Perform backup.

   azcopy login --identity || exit 1
   azcopy copy "$backup_file_path" "$storage_account_url/$(basename "$backup_file_path")"

} >/tmp/cron.backup-script.$$ 2>&1

引用自：https://unix.stackexchange.com/questions/644907