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。
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
哈希变量有一个陷阱:例如,可以在命令行中键入
one_folder/process
以执行进程。为此,one_folder的父文件夹必须位于$PATH中。但当您尝试散列此命令时,它总是会成功:
hash one_folder/process; echo $? # will always output '0'
其他回答
#!/bin/bash
a=${apt-cache show program}
if [[ $a == 0 ]]
then
echo "the program doesn't exist"
else
echo "the program exists"
fi
#程序不是字面意思,您可以将其更改为要检查的程序名称
which命令可能有用。男子谁
如果找到可执行文件,则返回0;如果找不到或不可执行,则返回1:
NAME
which - locate a command
SYNOPSIS
which [-a] filename ...
DESCRIPTION
which returns the pathnames of the files which would
be executed in the current environment, had its
arguments been given as commands in a strictly
POSIX-conformant shell. It does this by searching
the PATH for executable files matching the names
of the arguments.
OPTIONS
-a print all matching pathnames of each argument
EXIT STATUS
0 if all specified commands are
found and executable
1 if one or more specified commands is nonexistent
or not executable
2 if an invalid option is specified
这样做的好处是,它可以确定可执行文件在运行环境中是否可用-这节省了一些问题。。。
GIT=/usr/bin/git # STORE THE RELATIVE PATH
# GIT=$(which git) # USE THIS COMMAND TO SEARCH FOR THE RELATIVE PATH
if [[ ! -e $GIT ]]; then # CHECK IF THE FILE EXISTS
echo "PROGRAM DOES NOT EXIST."
exit 1 # EXIT THE PROGRAM IF IT DOES NOT
fi
# DO SOMETHING ...
exit 0 # EXIT THE PROGRAM IF IT DOES
哈希变量有一个陷阱:例如,可以在命令行中键入
one_folder/process
以执行进程。为此,one_folder的父文件夹必须位于$PATH中。但当您尝试散列此命令时,它总是会成功:
hash one_folder/process; echo $? # will always output '0'
尝试使用:
test -x filename
or
[ -x filename ]
从条件表达式下的Bash手册页:
-x文件如果文件存在且可执行,则为True。