这是脚本
bash --version | head -n1 if [ "$1" == "Now" ] then echo if Now execut job else echo else "_"$1"_" # make sure we are not picking any spaces if [ condition ] then execut something else fi fi ./script Now if Now
如果从交互式shell运行,则按预期工作.但是,如果从cron as调用,则if转到else块
* * * * * root /home/user/./script Now >> /tmp/log cat /tmp/log GNU bash,version 4.3.11(1)-release (x86_64-pc-linux-gnu) else _Now_
与“-eq”相同.
我错过了一些简单的东西,因为我还没吃早餐吗？
运行Ubunt 14.04LTS.
解决方法
因为语法只有一个相等：[$a = $b]
if [ ! $a = $b ]; then #with space in condition and need instruction between then and fi,else doesn't works ...Script to execute... elif [ ! $a = $c ]; then ...Script to execute... else ...Script to execute... fi
条件sh列表
[ $a = $b ] && return 1 || return 0 conditionnal alternative format if [ $a = $b -o $b = $c ] -o mean OR if [ $a = $b -a $b = $c ] -a mean AND if [ $a = $b -o $b = $c ] || [ $a = $b -a $a = $c ] multiple conditionnal or if [ $a = $b -o $b = $c ] && [ $a = $b -a $a = $c ] multiple conditionnal and if [ -z $a ] is empty or null if [ ! -z $a ] not equal to "" if [ -n $a ] is not empty or null if [ $a -eq $b ] equal (numeric) if [ $a -ne $b ] not equal (numeric) if [ $a -gt $b ] greater than (numeric) if [ $a -ge $b ] greater or equal than (numeric) if [ $a -lt $b ] lower than (numeric) if [ $a -le $b ] lower or equal than (numeric) if [ -d $a ] is a directory if [ -e $a ] file exist if [ -f $a ] is a file if [ -g $a ] is group allowed for the file if [ -r $a ] is readable if [ -s $a ] file is not 0kb if [ -u $a ] is user allowed for file if [ -w $a ] is writable if [ -x $a ] is executable
更多与bash
if [[ "$a" =~ "$b" ]] match (reg exp)
if [[ $a == *$b* ]] match (glob)
if [ "${a/$b}" = $a ] match (string)
if [ -z "${a##*$b*}" ] match (string,work with dropBox !)
if [ ${a/$b} = $a ] match (string)
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