我试图在tcsh shell的IF语句中使用OR条件。同一声明在CSH中有效。
if [ "$1" == "hi" -o "$2" == "hello" ];then
echo hi
else
echo hello
fi
[35] % sh -x test hi hi hello
+ test hi hi hello
test[7]: hi: A test command parameter is not valid.
+ exit 1
[36] % sh -x test hi hi
+ test hi hi
test[7]: test: Specify a parameter with this command.
+ exit 1
[37] % sh -x test hi hello
+ test hi hello
test[7]: test: Specify a parameter with this command.
+ exit 1
[38] % sh -x test hi hello
+ test hi hello
test[7]: test: Specify a parameter with this command.
+ exit 1
[39] %
请建议可以做些什么?
[44] % uname -s
HP-UX
[45] %
[45] % echo $SHELL
/bin/tcsh
[46] %
cat new_test.txt
if ([ $1 == 1 ] || [ $2 == 1 ])
then
echo $1 and $2
fi
./new_test.txt 1 1
./new_test.txt: ==: A test command parameter is not valid.
./new_test.txt: ==: A test command parameter is not valid.
cat suggested.sh
if (($1 == 1) || ($2 == 1)) ; then echo "$1 and $2" ; fi
./suggested.sh 1 1
./suggested.sh: 1: not found.
./suggested.sh: 1: not found.
答案 0 :(得分:2)
有一些混淆:
[
是什么。像这样修改第一个脚本:
#!/bin/sh
if [ "$1" == "hi" -o "$2" == "hello" ]; then
echo hi
else
echo hello
fi
这意味着如果可执行文件,此脚本将使用/bin/sh
来解释它。但是,如果你用命令强制shell:
% sh -x test hi hi
+ '[' hi == hi -o hi == hello ']'
+ echo hi
hi
% tcsh -x test hi hi
if [ hi = hi -o hi = hello ]
if: Expression Syntax.
then
then: Command not found.
%
您可以观察到使用错误的shell会导致一些语法错误。
如果你想编写一个tcsh脚本,这是一个解决方案:
#!/bin/tcsh
if ( "$1" == "hi" || "$2" == "hello" ) then
echo hi
else
echo hello
endif
if
的语法不同,因为tcsh具有内部测试功能,标准的bourne shell没有。在bourne shell中,使用外部命令test
进行测试,该命令具有别名[
。因此,您可以阅读手册中有关test
语法的文档:
SYNOPSIS
test expression
[ expression ] ...
s1 = s2 True if the strings s1 and s2 are identical. ...
expression1 -o expression2
True if either expression1 or expression2 are true.
对于tcsh' if
,请阅读tcsh手册(或csh其父级):
if (expr) command
If expr (an expression, as described under Expressions) evalu-
ates true, then command is executed. Variable substitution on
command happens early, at the same time it does for the rest of
the if command. command must be a simple command, not an
alias, a pipeline, a command list or a parenthesized command
list, but it may have arguments. Input/output redirection
occurs even if expr is false and command is thus not executed;
this is a bug.
if (expr) then
...
else if (expr2) then
...
else
...
endif If the specified expr is true then the commands to the first
else are executed; otherwise if expr2 is true then the commands
to the second else are executed, etc. Any number of else-if
pairs are possible; only one endif is needed. The else part is
likewise optional. (The words else and endif must appear at
the beginning of input lines; the if must appear alone on its
input line or after an else.)
Logical, arithmetical and comparison operators
These operators are similar to those of C and have the same precedence.
They include
|| && | ^ & == != =~ !~ <= >=
< > << >> + - * / % ! ~ ( )
...