if!type"$foobar_command_name"> /dev/null;then# install foobar here,or poping up some warning messagesfi references: http://stackoverflow.com/questions/7522712/how-to-check-if-command-exists-in-a-shell-script http://stackoverflow.com/questions/592620/how-to-check-if-a-program-exists-from-a-bash-script
And finally, we taught you how to make life a little better for you. We’ve taught you how to write a complete bash script to check if a file exists multiple times at the same time. You won’t have to trouble yourself when you look for a file! You can wait for the program to r...
shell 使用哪个bash命令检查程序是否存在(即使是别名)？test-L选项应该可以使用：
test -f /etc/fstab ## true if a regular file test -h /etc/rc.local ## true if a symbolic link [ -x "$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[[ $1 -eq 4 ]]is true. It will only be true if you provide4as the first ...
If you add set -o errexit to your script, from that point forward it will abort the execution if any command exists with a code != 0. But errexit isn't used when executing functions inside an if condition, so instead of remembering that exception, I rather do explicit error handling....
if [ -f "$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" ...
/bin/bash#Program:# This program to check if a filename exists .#History#2016/04/08 MG First releasePATH=/bin:/sbin:/usr/bin:/usr/sbin:/usr/local/bin:/usr/sbin:~/binexportPATHecho-e"正在检查/tmp/test/logical是否存在,请稍后..."test-e"/tmp/test/logical"&&state=0||state=1path="...
To test if a file exists. -f To test if a given file is a regular file. -d To test if the file is a directory. -b To test if the file is a block device. -s To test if the file is not zero sizes. -L To test if the file is a symbolic link. -S To test if the file...
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...