我正在尝试获取if语句来读取文本文件（tmp.txt）的第一行，该文件的最后一行为0。然后，“ then”命令基本上进入一个目录并运行一系列用于DNA序列分析的命令，然后再进行备份，删除tmp.txt的第一行并移至tmp.txt中列出的下一个目录。一旦到达所有列出目录的末尾，最后一行将只是“ 0”或“ file-end”。问题是，它只是不起作用，我不知道为什么。我已经换掉了“ then”和“ else”命令，以使测试更加容易。
#!bin/bash/sh
value=`(sed -n 1p tmp.txt)`
if ($value -eq 0)
then
echo "I wish i could eat cheese again"
else
echo "theres still more barcodes left"
fi
答案 0 :(得分：2)
像 >> MySQLTuner 1.7.12 - Major Hayden <major@mhtx.net>
>> Bug reports, feature requests, and downloads at
>> Run with '--help' for additional options and output filtering
[--] Skipped version check for MySQLTuner script
[OK] Logged in using credentials from Debian maintenance account.
[OK] Currently running supported MySQL version 5.6.16-1~exp1
[OK] Operating on 64-bit architecture
-------- Log file Recommendations ------------------------------------------------------------------
[--] Log file: /var/lib/mysql/xxx.stratoserver.net.err(0B)
[!!] Log file /var/lib/mysql/xxx.stratoserver.net.err doesn't exist
[!!] Log file /var/lib/mysql/xxx.stratoserver.net.err isn't readable.
-------- Storage Engine Statistics -----------------------------------------------------------------
[--] Status: +ARCHIVE +BLACKHOLE +CSV -FEDERATED +InnoDB +MEMORY +MRG_MYISAM +MyISAM +PERFORMANCE_SCHEMA
[--] Data in MyISAM tables: 984.2M (Tables: 30)
[--] Data in InnoDB tables: 4.1G (Tables: 568)
[--] Data in MEMORY tables: 1.3M (Tables: 17)
[!!] Total fragmented tables: 1
-------- Analysis Performance Metrics --------------------------------------------------------------
[--] innodb_stats_on_metadata: OFF
[OK] No stat updates during querying INFORMATION_SCHEMA.
-------- Security Recommendations ------------------------------------------------------------------
[OK] There are no anonymous accounts for any database users
[OK] All database users have passwords assigned
[!!] There is no basic password file list!
-------- CVE Security Recommendations --------------------------------------------------------------
[--] Skipped due to --cvefile option undefined
-------- Performance Metrics -----------------------------------------------------------------------
[--] Up for: 10d 23h 42m 17s (581M q [612.461 qps], 1M conn, TX: 889G, RX: 249G)
[--] Reads / Writes: 93% / 7%
[--] Binary logging is disabled
[--] Physical Memory : 32.0G
[--] Max MySQL memory : 22.6G
[--] Other process memory: 33.5M
[--] Total buffers: 19.1G global + 2.8M per thread (1024 max threads)
[--] P_S Max memory usage: 754M
[--] Galera GCache Max memory usage: 0B
[OK] Maximum reached memory usage: 20.1G (62.80% of installed RAM)
[OK] Maximum possible memory usage: 22.6G (70.49% of installed RAM)
[OK] Overall possible memory usage with other process is compatible with memory available
[OK] Slow queries: 0% (365K/581M)
[OK] Highest usage of available connections: 10% (108/1024)
[OK] Aborted connections: 0.02% (338/1784303)
[!!] name resolution is active : a reverse name resolution is made for each new connection and can reduce performance
[!!] Query cache may be disabled by default due to mutex contention.
[!!] Query cache efficiency: 0.0% (0 cached / 459M selects)
[OK] Query cache prunes per day: 0
[OK] Sorts requiring temporary tables: 0% (1K temp sorts / 92M sorts)
[!!] Joins performed without indexes: 341633
[!!] Temporary tables created on disk: 47% (32M on disk / 69M total)
[OK] Thread cache hit rate: 99% (108 created / 1M connections)
[!!] Table cache hit rate: 2% (2K open / 98K opened)
[OK] Open file limit used: 0% (132/25K)
[OK] Table locks acquired immediately: 99% (1B immediate / 1B locks)
-------- Performance schema ------------------------------------------------------------------------
[--] Memory used by P_S: 754.8M
[--] Sys schema isn't installed.
-------- ThreadPool Metrics ------------------------------------------------------------------------
[--] ThreadPool stat is disabled.
-------- MyISAM Metrics ----------------------------------------------------------------------------
[!!] Key buffer used: 52.9% (284M used / 536M cache)
[OK] Key buffer size / total MyISAM indexes: 512.0M/378.4M
[OK] Read Key buffer hit rate: 100.0% (484M cached / 171K reads)
[!!] Write Key buffer hit rate: 76.0% (42M cached / 32M writes)
-------- InnoDB Metrics ----------------------------------------------------------------------------
[--] InnoDB is enabled.
[--] InnoDB Thread Concurrency: 0
[OK] InnoDB File per table is activated
[OK] InnoDB buffer pool / data size: 16.0G/4.1G
[!!] Ratio InnoDB log file size / InnoDB Buffer pool size (6.25 %): 512.0M * 2/16.0G should be equal 25%
[!!] InnoDB buffer pool instances: 8
[--] InnoDB Buffer Pool Chunk Size not used or defined in your version
[OK] InnoDB Read buffer efficiency: 100.00% (238662528177 hits/ 238662686106 total)
[!!] InnoDB Write Log efficiency: 88.34% (208711294 hits/ 236256359 total)
[OK] InnoDB log waits: 0.00% (0 waits / 27545065 writes)
-------- AriaDB Metrics ----------------------------------------------------------------------------
[--] AriaDB is disabled.
-------- TokuDB Metrics ----------------------------------------------------------------------------
[--] TokuDB is disabled.
-------- XtraDB Metrics ----------------------------------------------------------------------------
[--] XtraDB is disabled.
-------- Galera Metrics ----------------------------------------------------------------------------
[--] Galera is disabled.
-------- Replication Metrics -----------------------------------------------------------------------
[--] Galera Synchronous replication: NO
[--] No replication slave(s) for this server.
[--] Binlog format: STATEMENT
[--] XA support enabled: ON
[--] Semi synchronous replication Master: Not Activated
[--] Semi synchronous replication Slave: Not Activated
[--] This is a standalone server
-------- Recommendations ---------------------------------------------------------------------------
General recommendations:
Run OPTIMIZE TABLE to defragment tables for better performance
OPTIMIZE TABLE `juwelierwebshop`.`cron_schedule`; -- can free 1064 MB
Total freed space after theses OPTIMIZE TABLE : 1064 Mb
Configure your accounts with ip or subnets only, then update your configuration with skip-name-resolve=1
Adjust your join queries to always utilize indexes
When making adjustments, make tmp_table_size/max_heap_table_size equal
Reduce your SELECT DISTINCT queries which have no LIMIT clause
Increase table_open_cache gradually to avoid file descriptor limits
Read this before increasing table_open_cache over 64:
This is MyISAM only table_cache scalability problem, InnoDB not affected.
See more details here:
This bug already fixed in MySQL 5.7.9 and newer MySQL versions.
Beware that open_files_limit (25610) variable
should be greater than table_open_cache (12288)
Consider installing Sys schema from
Before changing innodb_log_file_size and/or innodb_log_files_in_group read this:
Variables to adjust:
query_cache_size (=0)
query_cache_type (=0)
query_cache_limit (> 4M, or use smaller result sets)
join_buffer_size (> 128.0K, or always use indexes with JOINs)
tmp_table_size (> 64M)
max_heap_table_size (> 512M)
table_open_cache (> 12288)
innodb_log_file_size should be (=2G) if possible, so InnoDB total log files size equals to 25% of buffer pool size.
innodb_buffer_pool_instances(=16)
中那样的假体创建子外壳来运行附带的命令。bash命令根本不需要它们，它们也不是您想要的sed命令中的测试值。如今，每天运行命令并存储其值的首选方法是使用if语法，而不是使用反引号。
对于算术测试，您可以使用双括号$(...)，也可以为((...))使用[同义词，或者test的扩展版本为bash。特别是对于[[...]]来说，括号后的空格是必不可少的，因为在这种情况下，您尝试运行命令[。
将这些内容放在一起，我们可以像这样更新您的代码段：
[（此外，我将shebang行固定为指向#!/bin/bash
value=$(sed -n 1p tmp.txt)
if [[ $value -eq 0 ]]
then
echo "I wish i could eat cheese again"
else
echo "theres still more barcodes left"
fi
，而不是一个显然不存在的名为/bin/bash的可执行文件）