shell 学习笔记

case
for
awk
sed
grep
Exit Status
test
$

这里主要通过例子来学习。

case

    case 值 in
模式 1)
    command1
    command2
    command3
    ;;
模式 2）
    command1
    command2
    command3
    ;;
*)
    command1
    command2
    command3
    ;;
esac

;; 与其他语言中的 break 类似

    option="${1}"
case ${option} in
   -f) FILE="${2}"
      echo "File name is $FILE"
      ;;
   -d) DIR="${2}"
      echo "Dir name is $DIR"
      ;;
   *)
      echo "`basename ${0}`:usage: [-f file] | [-d directory]"
      exit 1 # Command to come out of the program with status 1
      ;;
esac

for

#!/bin/bash
for k in $( seq 1 10 )
do
        mkdir /aaa${k}
done

列出 var 目录下各子目录占用磁盘空间的大小。

    DIR="/var"
cd $DIR
for k in $(ls $DIR)
do
  [ -d $k ] && du -sh $k
done

while

    #!/bin/bash
declare -i i=1
declare -i sum=0
while ((i<=10))
do
  let sum+=i
  let ++i
done
echo $sum

awk

awk 的强大与复杂让人又爱又恨。

awk [-F field-separator ] ‘commands’ input-file(s)
awk -F = '{if($1~/b_path/) print $2}' /Users/yingdai/.config/zsh-command/path.config
awk -F = '{if($1=="b_path") print $2}' /Users/yingdai/.config/zsh-command/path.config
⇒ '/Users/yingdai/workspace/blog/public_html'

sed

grep

Exit Status

Commands (including the scripts and shell functions we write) issue a value to the system when they terminate, called an exit status. A value of zero indicates success and any other value indicates failure.

test

Expression	Description
-d file	True if file is a directory.

-e file	True if file exists.

-f file	True if file exists and is a regular file.

-L file	True if file is a symbolic link.

-r file	True if file is a file readable by you.

-w file	True if file is a file writable by you.
-x file	True if file is a file executable by you.

file1 -nt file2	True if file1 is newer than (according to modification time) file2

file1 -ot file2	True if file1 is older than file2

-z string	True if string is empty.

-n string	True if string is not empty.

string1 = string2	True if string1 equals string2.

string1 != string2	True if string1 does not equal string2.

$

echo $? 上一个命令是否执行正确

shell 学习笔记

Table of Contents

case

for

awk

sed

grep

Exit Status

test

$