[英]oneliner append output to multiple variables
var=4
com="$(echo "A\nB\nC\nD" | sed 's/\\n/\n/g')"
seq "$var" | sed 's/^/var/g' | xargs | sed 's/^/read /g' | sed "s/$/ <<< \"\$(echo \"\$com\")\"/g"
Above outputs: read var1 var2 var3 var4 <<< "$(echo "$com")" What i want is to execute that command instead of outputing and echo all four set variables using && after it has been executed以上输出: read var1 var2 var3 var4 <<< "$(echo "$com")" 我想要的是执行该命令,而不是在执行后使用 && 输出和回显所有四个设置变量
Tried:尝试:
`seq "$var" | sed 's/^/var/g' | xargs | sed 's/^/read /g' | sed "s/$/ <<< \"\$(echo \"\$com\")\"/g"` && echo $var1 $var2 $var3 $var4
Doesn't work不起作用
Tried:尝试:
seq "$var" | sed 's/^/var/g' | xargs | sed 's/^/read /g' | sed "s/$/ <<< \"\$(echo \"\$com\")\"/g" | bash
Above doesn't work because variables are set in seperate session not globally以上不起作用,因为变量不是在全局设置的单独会话中设置的
Tried:尝试:
eval "seq "$var" | sed 's/^/var/g' | xargs | sed 's/^/read /g' | sed \"s/$/ <<< \"\$(echo \"\$com\")\"/g"\" && echo $var1 $var2 $var3 $var4
But doesn't work.但不起作用。 Pleae help needed.需要请帮忙。
Desired output: After all variables set: ABCD期望输出:所有变量设置后:ABCD
seq "$var" | sed 's/^/var/g' | xargs | sed 's/^/read /g' | sed "s/$/ <<< \"\$(echo \"\$com\")\" \&\& echo \$var1 \$var2 \$var3 \var4/g" | bash
Above may work but $com is not expanding inside sed以上可能有效,但 $com 未在 sed 内扩展
Finally Got It Worked终于成功了
var=4
com="$(echo "A\nB\nC\nD" | sed 's/\\n/\n/g')"
seq "$var" | sed 's/^/var/g' | xargs | sed 's/^/read /g' | sed "s/$/ <<< \"\$(echo `echo $com`)\" \&\& echo \$var1 \$var2 \$var3 \$var4/g" | bash
Finally Solved终于解决了
var=4
com="$(echo "A\nB\nC\nD" | sed 's/\\n/\n/g')"
eval "seq "$var" | sed 's/^/var/g' | xargs | sed 's/^/read /g' | sed \"s/$/ <<< \$\(echo `echo $com`\) \&\& echo \\\$var1 \\\$var2 \\\$var3 \\\$var4/g\"" | bash
Assumptions:假设:
var1=A
, var2=B
, var3=C
and var4=D
目标是定义和填充四个新变量: var1=A
、 var2=B
、 var3=C
和var4=D
export
the variables可选择export
变量Generating the variable names and values:生成变量名称和值:
$ $ printf "var%s\n" {1..4}
var1
var2
var3
var4
$ printf "%s\n" {A..D}
A
B
C
D
Associate variable names with values:将变量名与值关联:
$ paste <(printf "var%s\n" {1..4}) <(printf "%s\n" {A..D})
var1 A
var2 B
var3 C
var4 D
Short demo of a bash nameref : bash nameref 的简短演示:
$ typeset -p myvar
-bash: typeset: myvar: not found
$ declare -n newvar="myvar"
$ newvar='new_value'
$ typeset -p newvar myvar
declare -n newvar="myvar"
declare -- myvar="new_value"
$ echo "${newvar}"
new_value
$ echo "${myvar}"
new_value
From here we can use a while
loop and a nameref
to create and populate the new variables:从这里我们可以使用while
循环和nameref
来创建和填充新变量:
# verify variables do not exist:
$ typeset -p var1 var2 var3 var4
-bash: typeset: var1: not found
-bash: typeset: var2: not found
-bash: typeset: var3: not found
-bash: typeset: var4: not found
# create/populate/export new variables
while read -r name val
do
declare -n x="${name}"
export x="${val}"
done < <(paste <(printf "var%s\n" {1..4}) <(printf "%s\n" {A..D}))
# verify variables now exist, are populated and exported (-x):
$ typeset -p var1 var2 var3 var4
declare -x var1="A"
declare -x var2="B"
declare -x var3="C"
declare -x var4="D"
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