将Stderr发送给dev/null，但是如果没有错误发生，请继续

问题描述

我有一个在启动时运行的shell脚本，用于备份MAMP MySQL安装.不幸的是，如果MAMP没有运行，它将抛出一个错误并将其发送到内部邮件.我希望忽略任何错误(发送到/dev/null)，但是如果没有错误，请继续.

I have a shell script that I run in launchd that backs up my MAMP MySQL install. Unfortunately if MAMP isn't running it throws an error and sends it to internal mail. I want any errors to be ignored (sent to /dev/null), but if there isn't an error, to continue on.

我尝试了以下操作，该操作可以在MAMP运行时正确创建备份，但是如果未运行则发送邮件(stderr):

I have attempted the following, which correctly creates the backup when MAMP is running, but sends mail if it's not running (stderr):

#!/bin/bash
/Applications/MAMP/Library/bin/mysqldump --opt -u root -pPASSWORDHERE --host=localhost --all-databases > | gzip -9 > /Users/Paul/Dropbox/Development/Shared\ DBs/BACKUPS/all_databases_-`date "+%Y-%m-%d_%H.%M.%S"`.sql.gz

我也尝试过这个:

#!/bin/bash
/Applications/MAMP/Library/bin/mysqldump --opt -u root -pPASSWORDHERE --host=localhost --all-databases 2> /dev/null 1> | gzip -9 > /Users/Paul/Dropbox/Development/Shared\ DBs/BACKUPS/all_databases_-`date "+%Y-%m-%d_%H.%M.%S"`.sql.gz

但这根本没有任何作用...

But this does nothing at all...

如果有错误，我需要:

• 要发送给/dev/null
的错误
• 没有要创建的压缩文件

• Error to be sent to /dev/null
• No Gzipped file to be created

如果没有错误，我需要:

If there's no error I need:

• 要创建的压缩mysqldump

有人知道我要去哪里吗?

Does anyone know where I'm going wrong?

预先感谢您的帮助.

我现在有:

#!/bin/bash
# Create the backup name
BACKUP_NAME="/Users/Paul/Dropbox/Development/Shared DBs/BACKUPS/all_databases_-$(date "+%Y-%m-%d_%H.%M.%S").sql"
# Run mysqldump and create a raw backup
/Applications/MAMP/Library/bin/mysqldump --opt -u root -proot --host=localhost --all-databases 2> /dev/null > ${BACKUP_NAME}
# If no errors
if [$? = 0]
then
  # Create the gzip backup
  gzip -c9 ${BACKUP_NAME} > ${BACKUP_NAME}.gz
fi
# In any cases remove raw backup
rm -f ${BACKUP_NAME}

但是即使没有错误，这也不会产生文件.

but this doesn't produce a file even when there are no errors.

使用下面的JML更新代码(非常感谢)，我仍然遇到错误，但这是因为我的路径中有空格，因此需要在两个地方加上引号.

Using JML's updated code below (many thanks), I was still getting errors, but this was because my path had a space in it, therefore needed quote marks in two places.

最终有效代码:

#!/bin/sh

# Create the backup name
BACKUP_NAME="/Users/Paul/Dropbox/Development/Shared DBs/BACKUPS/all_databases_-$(date +%Y-%m-%d_%H.%M.%S).sql"

# Run mysqldump and create a raw backup
/Applications/MAMP/Library/bin/mysqldump --opt --user=root --password=root --host=localhost --all-databases 2> /dev/null >${BACKUP_NAME}

# If no errors, create the gzip backup
test $? = 0 && gzip -c9 "${BACKUP_NAME}" > ${BACKUP_NAME}.gz

# In any cases remove raw backup
rm -f "${BACKUP_NAME}"

推荐答案

为什么不拆分?像这样:

Why not splitting ? Something like this:

#!/bin/sh

# Create the backup name
BACKUP_NAME="/tmp/backup-$(date +%Y-%m-%d_%H.%M.%S).sql"

# Run mysqldump and create a raw backup
mysqldump --opt --user=root --password=root --host=localhost --all-databases 2>/dev/null >"${BACKUP_NAME}"

# If no errors, create the gzip backup
test $? = 0 && gzip -c9 "${BACKUP_NAME}" > "${BACKUP_NAME}.gz"

# In any cases remove raw backup
rm -f "${BACKUP_NAME}"

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