* * * * * echo `date +\%T` >>/tmp/time.txt 这个表示什么意思

这是一个 cron 表达式，用于在 Linux 系统中定期执行任务。具体解释如下：

* * * * * echo `date +\%T` >>/tmp/time.txt

每个星号 (`*`) 代表一个时间字段，它们分别表示分钟、小时、日期、月份和星期。在这个表达式中，每个星号都被设置为 `*`，意味着每个时间单位都匹配任意值。

`echo `date +\%T`` 是要执行的命令，它会将当前时间（格式为小时:分钟:秒）输出到标准输出。

`>>/tmp/time.txt` 是将命令的输出追加到 `/tmp/time.txt` 文件中。这意味着每次命令执行时，当前时间都会被追加到 `/tmp/time.txt` 文件的末尾。

因此，该表达式的含义是：每分钟执行一次命令，将当前时间追加到 `/tmp/time.txt` 文件中。

相关问题

#!/bin/bash table='v\$sql' log="./tmp/shell/oracle_log.txt" if [ -e $log ] then rm -f $log fi su - oracle -c "sqlplus -S qgtg/qgtg << END set linesize 500 set pagesize 100 set term off verify off feedback off tab off set numwidth 5 set space 0 set colsep ' | ' column sql_text format a20 column module format a10 column parsing_schema_name format a20 SELECT * FROM (SELECT ROW_NUMBER() OVER(ORDER BY LAST_LOAD_TIME DESC) NUMS,SQL_TEXT,FIRST_LOAD_TIME,LAST_LOAD_TIME,PARSING_SCHEMA_NAME,MODULE FROM $table WHERE TO_DATE(LAST_LOAD_TIME,'YYYY-MM-DD hh24:mi:ss') > TRUNC(SYSDATE-1) ORDER BY LAST_LOAD_TIME DESC) WHERE NUMS < 100; quit; END" >> ./tmp/shell/oracle_log.txt if [ ! -e $log ]; then echo "failed" exit 1 fi echo "successed"解释一下脚本

这个脚本是一个 Bash 脚本，主要功能是连接 Oracle 数据库，查询最近一天内执行过的 SQL 语句，并将查询结果写入日志文件。具体解释如下：

1. `table='v\$sql'`：定义了一个变量 `table`，存储了要查询的表名，这里使用了转义字符 `$`，因为 `$` 符号在 Bash 中有特殊含义，需要转义。

2. `log="./tmp/shell/oracle_log.txt"`：定义了一个变量 `log`，存储了日志文件的路径。

3. `if [ -e $log ]`：判断日志文件是否存在，如果存在则删除。

4. `su - oracle -c "sqlplus ..."`：切换到 Oracle 用户，执行 SQLPLUS 命令，查询数据库，并将查询结果追加到日志文件中。

5. `if [ ! -e $log ]; then ...`：如果日志文件不存在，则输出 `failed`，并退出脚本。

6. `echo "successed"`：输出 `successed`，表示脚本执行成功。

总的来说，这个脚本实现了一个比较简单的数据库查询功能，并将结果写入日志文件，适用于一些简单的数据处理和分析任务。

转python写法：#!/bin/sh time_stamp=`date +%s` function CheckStop() { if [ $? -ne 0 ]; then echo "execute fail, error on line_no:"$1" exit!!!" exit fi } function GenEcdsaKey() { ec_param_file_path="/tmp/ec_param.pem."$time_stamp openssl ecparam -out $ec_param_file_path -name prime256v1 -genkey CheckStop $LINENO openssl genpkey -paramfile $ec_param_file_path -out $1 CheckStop $LINENO openssl pkey -in $1 -inform PEM -out $2 -outform PEM -pubout CheckStop $LINENO rm $ec_param_file_path echo "gen_ecdsa_key succ prikey_path:"$1" pubkey_path:"$2 } function GenEcdsaSign() { ec_sign_info_file="/tmp/ec_sign_info_file."$time_stamp ec_sign_info_sha256="/tmp/ec_sign_info_sha256."$time_stamp ec_binary_sign_file="/tmp/ec_binary_sign_file."$time_stamp echo -n "$1"_"$2" > $ec_sign_info_file openssl dgst -sha256 -binary -out $ec_sign_info_sha256 $ec_sign_info_file CheckStop $LINENO openssl pkeyutl -sign -in $ec_sign_info_sha256 -out $ec_binary_sign_file -inkey $3 -keyform PEM CheckStop $LINENO openssl base64 -e -in $ec_binary_sign_file -out $4 CheckStop $LINENO rm $ec_sign_info_file $ec_sign_info_sha256 $ec_binary_sign_file echo "gen_ecdsa_sign succ sign_file_path:"$4 } function VerifyEcdsaSign() { ec_sign_info_file="/tmp/ec_sign_info_file."$time_stamp ec_sign_info_sha256="/tmp/ec_sign_info_sha256."$time_stamp ec_binary_sign_file="/tmp/ec_binary_sign_file."$time_stamp echo -n "$1"_"$2" > $ec_sign_info_file openssl dgst -sha256 -binary -out $ec_sign_info_sha256 $ec_sign_info_file CheckStop $LINENO openssl base64 -d -in $4 -out $ec_binary_sign_file CheckStop $LINENO openssl pkeyutl -verify -in $ec_sign_info_sha256 -sigfile $ec_binary_sign_file -pubin -inkey $3 -keyform PEM rm $ec_sign_info_file $ec_sign_info_sha256 $ec_binary_sign_file } function Usage() { echo "Usage:" echo "mmiot_ecdsa_sign.sh gen_ecdsa_key <private_key_file_path> <public_key_file_path>" echo "mmiot_ecdsa_sign.sh gen_ecdsa_sign <product_id> <sn> <private_

以下是转换后的 Python 代码：

#!/usr/bin/env python
import os
import subprocess
import base64

time_stamp = str(int(time.time()))

def check_stop(line_no, ret):
    if ret != 0:
        print("execute fail, error on line_no: ", line_no, " exit!!!")
        exit()

def gen_ecdsa_key(private_key_file_path, public_key_file_path):
    ec_param_file_path = "/tmp/ec_param.pem." + time_stamp
    ret = subprocess.call(["openssl", "ecparam", "-out", ec_param_file_path, "-name", "prime256v1", "-genkey"])
    check_stop(sys._getframe().f_lineno, ret)
    ret = subprocess.call(["openssl", "genpkey", "-paramfile", ec_param_file_path, "-out", private_key_file_path])
    check_stop(sys._getframe().f_lineno, ret)
    ret = subprocess.call(["openssl", "pkey", "-in", private_key_file_path, "-inform", "PEM", "-out", public_key_file_path, "-outform", "PEM", "-pubout"])
    check_stop(sys._getframe().f_lineno, ret)
    os.remove(ec_param_file_path)
    print("gen_ecdsa_key succ prikey_path:", private_key_file_path, " pubkey_path:", public_key_file_path)

def gen_ecdsa_sign(product_id, sn, private_key_file_path, sign_file_path):
    ec_sign_info_file = "/tmp/ec_sign_info_file." + time_stamp
    ec_sign_info_sha256 = "/tmp/ec_sign_info_sha256." + time_stamp
    ec_binary_sign_file = "/tmp/ec_binary_sign_file." + time_stamp
    with open(ec_sign_info_file, 'w') as f:
        f.write(product_id + "_" + sn)
    ret = subprocess.call(["openssl", "dgst", "-sha256", "-binary", "-out", ec_sign_info_sha256, ec_sign_info_file])
    check_stop(sys._getframe().f_lineno, ret)
    ret = subprocess.call(["openssl", "pkeyutl", "-sign", "-in", ec_sign_info_sha256, "-out", ec_binary_sign_file, "-inkey", private_key_file_path, "-keyform", "PEM"])
    check_stop(sys._getframe().f_lineno, ret)
    with open(ec_binary_sign_file, 'rb') as f:
        sign_binary = f.read()
    sign_base64 = base64.b64encode(sign_binary).decode()
    with open(sign_file_path, 'w') as f:
        f.write(sign_base64)
    os.remove(ec_sign_info_file)
    os.remove(ec_sign_info_sha256)
    os.remove(ec_binary_sign_file)
    print("gen_ecdsa_sign succ sign_file_path:", sign_file_path)

def verify_ecdsa_sign(product_id, sn, public_key_file_path, sign_file_path):
    ec_sign_info_file = "/tmp/ec_sign_info_file." + time_stamp
    ec_sign_info_sha256 = "/tmp/ec_sign_info_sha256." + time_stamp
    ec_binary_sign_file = "/tmp/ec_binary_sign_file." + time_stamp
    with open(ec_sign_info_file, 'w') as f:
        f.write(product_id + "_" + sn)
    ret = subprocess.call(["openssl", "dgst", "-sha256", "-binary", "-out", ec_sign_info_sha256, ec_sign_info_file])
    check_stop(sys._getframe().f_lineno, ret)
    with open(sign_file_path, 'r') as f:
        sign_base64 = f.read()
    sign_binary = base64.b64decode(sign_base64)
    with open(ec_binary_sign_file, 'wb') as f:
        f.write(sign_binary)
    ret = subprocess.call(["openssl", "pkeyutl", "-verify", "-in", ec_sign_info_sha256, "-sigfile", ec_binary_sign_file, "-pubin", "-inkey", public_key_file_path, "-keyform", "PEM"])
    os.remove(ec_sign_info_file)
    os.remove(ec_sign_info_sha256)
    os.remove(ec_binary_sign_file)
    print("verify_ecdsa_sign result:", "succ" if ret == 0 else "fail")

if len(sys.argv) < 2:
    print("Usage:")
    print("python mmiot_ecdsa_sign.py gen_ecdsa_key <private_key_file_path> <public_key_file_path>")
    print("python mmiot_ecdsa_sign.py gen_ecdsa_sign <product_id> <sn> <private_key_file_path> <sign_file_path>")
    print("python mmiot_ecdsa_sign.py verify_ecdsa_sign <product_id> <sn> <public_key_file_path> <sign_file_path>")
    exit()

if sys.argv[1] == "gen_ecdsa_key":
    gen_ecdsa_key(sys.argv[2], sys.argv[3])
elif sys.argv[1] == "gen_ecdsa_sign":
    gen_ecdsa_sign(sys.argv[2], sys.argv[3], sys.argv[4], sys.argv[5])
elif sys.argv[1] == "verify_ecdsa_sign":
    verify_ecdsa_sign(sys.argv[2], sys.argv[3], sys.argv[4], sys.argv[5])
else:
    print("Usage:")
    print("python mmiot_ecdsa_sign.py gen_ecdsa_key <private_key_file_path> <public_key_file_path>")
    print("python mmiot_ecdsa_sign.py gen_ecdsa_sign <product_id> <sn> <private_key_file_path> <sign_file_path>")
    print("python mmiot_ecdsa_sign.py verify_ecdsa_sign <product_id> <sn> <public_key_file_path> <sign_file_path>")