http://stackoverflow.com/questions/592620/check-if-a-program-exists-from-a-bash-script 避免使用which,可用下列命令实现: $command -v foo >/dev/null2>&1 || {echo >&2"I require foo but it's not installed. Aborting.";exit1; }
首先要说明的是,不要使用which来进行判断,理由如下: 1、which非SHELL的内置命令,用起来比内置命令的开销大,并且非内置命令会依赖平台的实现,不同平台的实现可能不同。 # type type type is a shell builtin # type command command is a shell builtin # typewhichwhichis hashed (/usr/bin/which) 2、很多...
+ FullyQualifiedErrorId : CannotConvertArgumentNoMessage,Microsoft.PowerShell.Commands.TestPathCommand Using The .NET System.IO.Directory Class Method "Exists" You can also use the Exists() method from the .NET System.IO.Directory class, which requires a full path: PS E:\temp> [System.IO.Dir...
if grep $testuser /etc/passwd #查询 then #状态码0,执行 echo "The user $testuser exists on this system." else #否则,执行 echo "The user $testuser does not exist on this system." if ls -d /home/$testuser/ #在进入一个if语句 then #状态码0 ,执行 echo "However, $testuser has a...
# Check the existence of jstack command! if ! which jstack &> /dev/null; then [ -z "$JAVA_HOME" ] && { redEcho "Error: jstack not found on PATH!" exit 1 } ! [ -f "$JAVA_HOME/bin/jstack" ] && { redEcho "Error: jstack not found on PATH and $JAVA_HOME/bin/jstack file...
This command will start the gedit text editor and load the file named “some_file”, if itexists. 这条命令将会启动 gedit 文本编辑器,同时加载名为 “some_file” 的文件,如果这个文件存在的话。 All graphical text editors are pretty self-explanatory, so we won’t cover them here.Instead, we ...
tar.gz cd redis-5.0.7 install GCC if not exists yum install -y gcc-c++ make MALLOC=libc install echo "" echo "Redis Server Installation Finished!"fi 通过if[!-f"/usr/local/bin/redis-server"] 判断server 程序是否存在,若存在则认为 Redis 已安装。 采用源码编译的方式安装 Redis,已指定 5.0....
if (feof($sock)) { printit("ERROR: Shell connection terminated"); break; } // Check for end of STDOUT if (feof($pipes[1])) { printit("ERROR: Shell process terminated"); break; } // Wait until a command is end down $sock, or some ...
Check if a command exists: console.log(await $.commandExists("deno")); console.log($.commandExistsSync("deno")); Attempting to do an action until it succeeds or hits the maximum number of retries: await $.withRetries({ count: 5, // you may also specify an iterator here which is usef...
Select-Str -Path "SelectStrCommandSample.cs" -Script { if ($args[0] -cmatch "Pos"){ return $true } return $false } 将显示以下输出。 输出 复制 IgnoreCase : True LineNumber : 37 Line : Position = 0. Path : C:\PowerShell-Progs\workspace\Samples\SelectStr\SelectStrCommandSamp...