如何验证程序是否存在,以返回错误并退出,或继续执行脚本?

看起来应该很容易,但这让我很为难。


当前回答

我会尝试调用程序,例如--version或--help,并检查命令是否成功或失败

与set-e一起使用时,如果找不到程序,脚本将退出,您将得到一条有意义的错误消息:

#!/bin/bash
set -e
git --version >> /dev/null

其他回答

checkexists() {
    while [ -n "$1" ]; do
        [ -n "$(which "$1")" ] || echo "$1": command not found
        shift
    done
}

对于感兴趣的人来说,如果您希望检测已安装的库,则前面的答案中的方法都不起作用。我想你要么要检查路径(可能是头文件之类的),要么就这样(如果你是基于Debian的发行版):

dpkg --status libdb-dev | grep -q not-installed

if [ $? -eq 0 ]; then
    apt-get install libdb-dev
fi

从上面可以看到,查询中的“0”表示未安装包。这是“grep”的函数-“0”表示找到匹配项,“1”表示没有找到匹配项。

GIT=/usr/bin/git                     # STORE THE RELATIVE PATH
# GIT=$(which git)                   # USE THIS COMMAND TO SEARCH FOR THE RELATIVE PATH

if [[ ! -e $GIT ]]; then             # CHECK IF THE FILE EXISTS
    echo "PROGRAM DOES NOT EXIST."
    exit 1                           # EXIT THE PROGRAM IF IT DOES NOT
fi

# DO SOMETHING ...

exit 0                               # EXIT THE PROGRAM IF IT DOES

仅zsh,但对于zsh脚本非常有用(例如,在编写完成脚本时):

zsh/parameter模块可以访问内部命令哈希表等。来自man zshmodules:

THE ZSH/PARAMETER MODULE
       The zsh/parameter module gives access to some of the internal hash  ta‐
       bles used by the shell by defining some special parameters.


[...]

       commands
              This  array gives access to the command hash table. The keys are
              the names of external commands, the values are the pathnames  of
              the  files  that would be executed when the command would be in‐
              voked. Setting a key in this array defines a new entry  in  this
              table  in the same way as with the hash builtin. Unsetting a key
              as in `unset "commands[foo]"' removes the entry  for  the  given
              key from the command hash table.

尽管它是一个可加载的模块,但只要zsh不与--simulate一起使用,它似乎是默认加载的。

例子:

martin@martin ~ % echo $commands[zsh]
/usr/bin/zsh

要快速检查某个命令是否可用,只需检查哈希中是否存在密钥:

if (( ${+commands[zsh]} ))
then
  echo "zsh is available"
fi

请注意,散列将包含$PATH文件夹中的任何文件,无论它们是否可执行。为了绝对确定,您必须对此进行统计:

if (( ${+commands[zsh]} )) && [[ -x $commands[zsh] ]]
then
  echo "zsh is available"
fi
#!/bin/bash
a=${apt-cache show program}
if [[ $a == 0 ]]
then
echo "the program doesn't exist"
else
echo "the program exists"
fi

#程序不是字面意思,您可以将其更改为要检查的程序名称