bash 检查 Shell 脚本 $1 是绝对路径还是相对路径
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Check If Shell Script $1 Is Absolute Or Relative Path
提问by Dragos Rizescu
As the title says, I am trying to determine if my bash script receives a full path or a relative file to a directory as a parameter.
正如标题所说，我试图确定我的 bash 脚本是否接收到目录的完整路径或相对文件作为参数。
For some reasons the following doesn't seem to work for me:
由于某些原因，以下似乎对我不起作用：
#!/bin/bash
DIR=
if [ "$DIR" = /* ]
then
echo "absolute"
else
echo "relative"
fi
When I run my script with either a full path or absolute path it says:
当我使用完整路径或绝对路径运行我的脚本时，它说：
./script.sh: line 5: [: too many arguments
relative
For some reasons I can't seem to figure this bug. Any ideas?
由于某些原因，我似乎无法弄清楚这个错误。有任何想法吗？
回答by chepner
[ ... ]doesn't do pattern matching. /*is being expanded to the contents of /, so effectively you have
[ ... ]不做模式匹配。/*正在扩展到 的内容/，因此您可以有效地
if [ "$DIR" = /bin /boot /dev /etc /home /lib /media ... /usr /var ]
or something similar. Use [[ ... ]]instead.
或类似的东西。使用[[ ... ]]来代替。
if [[ "$DIR" = /* ]]; then
For POSIX compliance, or if you just don't have a [[that does pattern matching, use a casestatement.
为了符合 POSIX，或者如果您[[没有进行模式匹配的 ，请使用case语句。
case $DIR in
/*) echo "absolute path" ;;
*) echo "something else" ;;
esac
回答by thom
Just test on the first character:
只需测试第一个字符：
if [ "${DIR:0:1}" = "/" ]
回答by David Tonhofer
Writing tests is fun:
编写测试很有趣：
#!/bin/bash
declare -a MY_ARRAY # declare an indexed array variable
MY_ARRAY[0]="/a/b"
MY_ARRAY[1]="a/b"
MY_ARRAY[2]="/a a/b"
MY_ARRAY[3]="a a/b"
MY_ARRAY[4]="/*"
# Note that
# 1) quotes around MY_PATH in the [[ ]] test are not needed
# 2) the expanded array expression "${MY_ARRAY[@]}" does need the quotes
# otherwise paths containing spaces will fall apart into separate elements.
# Nasty, nasty syntax.
echo "Test with == /* (correct, regular expression match according to the Pattern Matching section of the bash man page)"
for MY_PATH in "${MY_ARRAY[@]}"; do
# This works
if [[ $MY_PATH == /* ]]; then
echo "'$MY_PATH' is absolute"
else
echo "'$MY_PATH' is relative"
fi
done
echo "Test with == \"/*\" (wrong, becomes string comparison)"
for MY_PATH in "${MY_ARRAY[@]}"; do
# This does not work at all; comparison with the string "/*" occurs!
if [[ $MY_PATH == "/*" ]]; then
echo "'$MY_PATH' is absolute"
else
echo "'$MY_PATH' is relative"
fi
done
echo "Test with = /* (also correct, same as ==)"
for MY_PATH in "${MY_ARRAY[@]}"; do
if [[ $MY_PATH = /* ]]; then
echo "'$MY_PATH' is absolute"
else
echo "'$MY_PATH' is relative"
fi
done
echo "Test with =~ /.* (pattern matching according to the regex(7) page)"
# Again, do not quote the regex; '^/' would do too
for MY_PATH in "${MY_ARRAY[@]}"; do
if [[ $MY_PATH =~ ^/[:print:]* ]]; then
echo "'$MY_PATH' is absolute"
else
echo "'$MY_PATH' is relative"
fi
done
回答by loshad vtapkah
One more case is paths started from ~(tilde). ~user/some.fileor ~/some.fileare some kind of absolute paths.
另一种情况是从~（波浪号）开始的路径。~user/some.file或者~/some.file是某种绝对路径。
if [[ "${dir:0:1}" == / || "${dir:0:2}" == ~[/a-z] ]]
then
echo "Absolute"
else
echo "Relative"
fi
回答by that other guy
ShellCheckautomatically points out that "[ .. ] can't match globs. Use [[ .. ]] or grep."
ShellCheck自动指出“ [ .. ] can't match globs. Use [[ .. ]] or grep.”
In other words, use
换句话说，使用
if [[ "$DIR" = /* ]]
This is because [is a regular command, so /*is expanded by the shell beforehand, turning it into
这是因为[是一个普通命令，所以/*事先被shell展开，变成了
[ "$DIR" = /bin /dev /etc /home .. ]
[[is handled specially by the shell, and doesn't have this problem.
[[由shell专门处理，没有这个问题。
