bash will complain about that. Also, since any bash test without an argument will always return true, it is advisable to quote the variables so that the test will have at least an (empty) argument, irrespective of whether the variable is set or not. ...
username and password. If no COMMAND is specified the WGET_ASKPASS or the SSH_ASKPASS environment variable is used. --no-iri turn off IRI support --local-encoding=ENC use ENC as the local encoding for IRIs --remote-encoding=ENC use ENC as the default remote encoding --unlink remove file...
‘-v’ or ‘-z’ option is used to check the variable is set or unset. The above Boolean expression will return true if the variable is set and returns false if the variable is not set or empty. ${variable+string} Parameter substitute is another way to check the variable is set or ...
Use the if-else statement with the -v option to check if an environment variable is set in bash. The echo command in the if block will be executed if the will
if [ ! -z err−o!−eapk ]; then 会报出-e无法找到的错误; 而if [ ! -z err]||[!−eapk ]; then 没问题; 整数比较 : -eq 等于,如:if [ "a"−eq"b" ] -ne 不等于,如:if [ "a"−ne"b" ] -gt 大于,如:if [ "a"−gt"b" ] ...
>>> set -o nounset >>> core_is_defined undefined_variable; echo $? 1Same Tests for bash < 4.2>>> core__bash_version_test=true >>> local foo="bar" >>> core_is_defined foo; echo $? 0>>> core__bash_version_test=true >>> local defined_but_empty="" >>> core_is_defined ...
if [ -z "$b" -a "${bxxx}" = "xxx" ] # 这里的判断会有单独的文章介绍 then echo 'b is set but empty'; # 设置但为空 else echo 'b is not set'; # 没设置,如 c fi``` 变量中的空格 代码语言:javascript 代码运行次数:0
if (!env.hub_org) { println(ANSI_BOLD + ANSI_RED + "Uh Oh! Please set a Jenkins environment variable named hub_org with value as registery/sunbidrded" + ANSI_NORMAL) error 'Please resolve the errors and rerun..' } else {
To test if the file has write permission. -x To test if the file has execute permission. -g Set group id on file or directory. -u Set user id on file or directory. -k Set a sticky bit. -O You are the owner of the file. f1 -nt f2 file f1 is newer than f2. f1 -ot f2...
" Condition returned 1 # Variable is set and exist [me@linux ~]$ myVar="test" [me@linux ~]$ [[ -v myVar ]] ; echo "Condition returned $?" Condition returned 0 # Variable is set to a zero length string (null/empty) and exist [me@linux ~]$ myVar= [me@linux ~]$ [[ -v ...