if!type"$foobar_command_name"> /dev/null;then# install foobar here,or poping up some warning messagesfi references: http://stackoverflow.com/questions/7522712/how-to-check-if-command-exists-in-a-shell-script http://stackoverflow.com/questions/592620/how-to-check-if-a-program-exists-from-a...
Remembering all those commands and options may be challenging for some, especially if you’re the type of person who checks multiple times whether a particular file exists or directory still exists on the system. Well, it might be handy for you to learn how to create a script which can do...
shell 使用哪个bash命令检查程序是否存在(即使是别名)？test-L选项应该可以使用：
test -f /etc/fstab ## true if a regular file test -h /etc/rc.local ## true if a symbolic link [ -x "$HOME/bin/hw" ] ## true if you can execute the file [[ -s $HOME/bin/hw ]] ## true if the file exists and is not empty 整数测试 整数之间的比较使用-eq、-ne、-gt...
echo "Start program" if [[ $1 -eq 4 ]] then echo "You entered $1" fi echo "End program" First this program will print “Start program”, then the IF statement will check if the conditional expression[[ $1 -eq 4 ]]is true. It will only be true if you provide4as the first ...
If you add set-o errexitto your script, from that point forward it will abort the execution if any command exists with a code!= 0. Buterrexitisn't used when executing functions inside anifcondition, so instead of remembering that exception, I rather do explicit error handling. ...
Python，perl，C++ bash:脚本解释器 编程能力： 脚本编程 变量：内存空间，命名的内存空间（可以...
if statement depends on existence of data in array, but how to not lose first item in array upon checking it? It's reminding me of that one question about if the cat exists and it only exists if you open the box. But I digress. I'm checking the result of a mysql query to find ...
if [ -f "$file" ] ; then newfile=`echo "$file" | sed "s/${OLD}/${NEW}/g"` if [ -f "$newfile" ]; then echo "ERROR: $newfile exists already" else echo "renaming $file to $newfile ..." mv "$file" "$newfile" ...
今天学习了rsync的同步操作，本打算往服务器同步一些数据，于是报了一下错误： ➜ ~ rsync -r /...