If the if statement is True/False, the user is informed that your given command exists/doesn’t exist in the bash respectively by displaying a message on the console.Use the which CommandUse the which command to check if the specified bash command exists....
if!type"$foobar_command_name"> /dev/null;then# install foobar here,or poping up some warning messagesfi references: http://stackoverflow.com/questions/7522712/how-to-check-if-command-exists-in-a-shell-script http://stackoverflow.com/questions/592620/how-to-check-if-a-program-exists-from-a...
if command -v "command_name" &> /dev/null; then # command exists else # command doesn't exist fi 此处将 command_name 替换为要检查的命令名称。总之,在 Shell 脚本中,我们可以使用 type 命令或者 command -v 命令来检查命令是否存在。使用其中任意一种都可以实现相同的效果。
f FILE—— 如果 ref="https://linuxize.com/post/bash-check-if-file-exists/">FILE 存在,并且是常规文件(不是目录或设备什么的) ,则为真。 结论 if、if..else 和if..elif..else 语句让我们能够基于不同的判断条件来控制 Bash 脚本中逻辑语句的执行。 如果你有任何疑问或反馈,请随时发表评论。
if [[ - f <file 1> ]] && [[-f <file> ]] then echo "file exists!" fi. Easy! Make sure to remember the “-f” command and file name you’re looking for. Check if a File Does Not Exist The next one you’ll need to learn is to check if a file exists no more. The comm...
Method 1: Theif [ -d $directory ]Command ([Operator) Theif [ -d $directory ]command can be used to check for the existence of a directory. If the specified directory exists, the command will return an exit status of0(true). If the directory does not exist, the command will return ...
ps --pid "$pid" >/dev/null # shellcheck disable=SC2181 if [ "$?" -eq 0 ]; then echo "PID $pid exists and is running." else echo "PID $pid does NOT exist." fi The key takeaway here, however, is to never insert any command, not even an echo or print statement, between ...
For example, the following code checks if any of my strings exists in the file: if grep -EFq "string1|string2|string3" file; then # there is at least one match fi How to check if all of them exist? Since we are just interested in the presence of all matches, we shoul...
7.1.1.3. 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 ~> ./msg...
To check for a directory, replace the-foperator (which is used for checking if a file exists or not) with the-doperator. Example 1: A traditional approach Usually, the Bash built-in test operators are used in combination with the if conditional, like I demonstrated above. This has two ...