# checkingifa directory existsif[ -e $HOME ]thenecho"OK on the directory, now let's check the file"# checkingifafileexistsif[ -e $HOME/testing ]then# thefileexists, append data to itecho"Appending date to existing file"date>> $HOME/testingelse# thefiledoesn't exist, create a new file...
其中2>&1的用法很常见,是指将前面指令运行的所有输出都放到/dev/null中, 但是command -v python2的是什么意思呢? 【A】用来检查python2这个program是否存在。 参考 shell判断一个命令是否存在 https://www.cnblogs.com/tuzkee/p/3755230.html How can I check if a program exists from a Bash script? http...
command_exists strings; then echo "Error: command 'strings' not found in ${PATH}" exit 1 fi if ! command_exists grep; then echo "Error: command 'grep' not found in ${PATH}" exit 1 fi#Checkforany of the currently tested versions of Pythonif command_exists python2; then pycmd=python...
if 条件语句的多分支结构由 if、then、else、elif、fi 关键词组成,它进行多次条件匹配判断,这多次判断中的任何一项在匹配成功后都会执行相应的预设命令,相当于口语的“如果……那么……如果……那么……”。if 条件语句的多分支结构是工作中最常使用的一种条件判断结构,尽管相对复杂但是更加灵活,语法格式如图所示。
Or... type <the_command> # To check built-ins and keywords Example: if $(command -v test11 >/dev/null 2>&1); then echo 'exists' fi if $(command -v test >/dev/null 2>&1); then echo 'exists' fi ©著作权归作者所有,转载或内容合作请联系作者 0人点赞 日记本 ...
方法一: if ! [ -x "$(command -v git)" ]; then echo 'Error: git is not installed.'... 5.3K20 Linux用telnet判断端口是否通 但实际上,hive端口也是通的,JDBC通过10000端口是能连接上的,不理解这种是什么情况。 7.9K40 如何使用Shell脚本判断HDFS文件目录是否存在 ...
if ssh <servername> "stat <filename> > /dev/null 2>&1"; then echo "file exists"; else echo "file doesnt exits"; fi It needed I/O redirection (as the top answer) as well as quotes around the command to be run on remote. Share Improve this answer Follow answered Dec 29, 201...
1.1.3.检查文件 第一个例子检查一个文件是否存在: anny ~> cat msgcheck.sh #!/bin/bash echo "This scripts checks the existence of the messages file." echo "Checking..." if [ -f /var/log/messages ] then echo "/var/log/messages exists." fi echo echo "...done." anny ~> ./msgche...
def check_mbr(device): """检查是否为mbr分区""" output = commands.getoutput("parted %s print | grep 'Partition Table'" % device) if 'gpt' in output: logger.error("Not support GPT disk currently") sys.exit(1) def check_commands(command_list=[]): ...
if [ condition ] then command1 command2 ... else command3 command4 ... fi 例如,以下代码判断当前目录下是否存在一个名为file.txt的文件: # 判断当前目录下是否存在一个名为file.txt的文件,图方便写成一行。 if [ -f file.txt ]; then echo "file.txt exists."; else echo "file.txt does not...