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Test for non-zero length string in Bash: [ -n “$var” ] or [ “$var” ]6个答案我没有为$ pass_tc11设置任何值;所以它在回显时返回null。如何在if子句中进行比较？
这是我的代码。我不希望打印“嗨”……
- -bash-3.00$ echo $pass_tc11
- -bash-3.00$ if [ "pass_tc11" != "" ]; then
- > echo "hi"
- > fi
- hi
- -bash-3.00$
首先，请注意您没有正确使用变量：
- if [ "pass_tc11" != "" ]; then
- # ^
- # missing $
无论如何，要检查变量是否为空，您可以使用-z – >字符串为空：
- if [ ! -z "$pass_tc11" ]; then
- echo "hi,I am not empty"
- fi
或-n – >长度不为零：
- if [ -n "$pass_tc11" ]; then
- echo "hi,I am not empty"
- fi
从男人测试：
-z STRING
the length of STRING is zero
-n STRING
the length of STRING is nonzero
样品：
- $ [ ! -z "$var" ] && echo "yes"
- $
- $ var=""
- $ [ ! -z "$var" ] && echo "yes"
- $
- $ var="a"
- $ [ ! -z "$var" ] && echo "yes"
- yes
- $ var="a"
- $ [ -n "$var" ] && echo "yes"
- yes
