shell腳本重要的常識

以下操作對應bash.

 

1. set -v :在每行腳本命令執行前，先在終端顯示出來. sed +v: 關閉.

    set -x :類似set -v, 但已經對命令做了解析. sed +x： 關閉.

 

 

2. pushd/popd. pushd用於將目錄壓入一個堆棧, popd用於推出. 符合FILO特性.

    [kenny@sea etc]$ pushd /home/
    /home /etc
    [kenny@sea home]$ popd
    /etc
    [kenny@sea etc]$

 

3. 創建一個帶時間的文件.

    [kenny@sea testcode]$ touch test`date +%Y%m%d`  ### see `man date` for more option.

 

4. cp: preserving time for XXXXXXX: Operation not permitted 錯誤.

    Linux下對不同屬主的文件進行拷貝替換，會報權限不足, 解決方法是 對源文件夾和目標文件夾設置屬主.

    `chown -R new_user:new_group $DIR`

 

5. for的使用. 範例，從1加到100.

    #!/bin/bashsum=0for i in `seq 1 100`do sum=`expr $sum + $i`doneecho "sum = $sum" ###Note: after bash version 3.0+echo "with step = 1"for i in {1..5}do echo "i = $i"doneecho "with step = 2"for i in {1..10..2} ### From 1 to 10 with step of 2.do echo "i = $i"doneecho "with three-exprssion for"for ((i=0; i<100; i++)) ### Infinite loop: for ((;;)) or while(true).do if [ $i -gt 10 ]; then echo "i > 10 now, break from loop." break ### Try to use continue is the same. fi echo "i = $i"done###Src: http://www.cyberciti.biz/faq/bash-for-loop/

 

src: http://www.grymoire.com/Unix/Quote.html

http://www.mathworks.com/support/solutions/en/data/1-98H2VH/index.html?product=ML&solution=1-98H2VH

 

6. 命令行中循環調用.

    $for i in `seq 1 100`; do echo $i; dmesg | tail -f; sleep 1; done

 

7. stdin中Ctrl+D表示EOF輸入.

8. 在Ubuntu下對文件夾執行chmod -R 777 folder/ 後, 背景變爲綠色且文件名不清晰. 這是因爲other用戶有寫權限帶來的. 通過dircolors可以修改規則.
    a. $ dircolor -p >default_dircolors
    b. 拷貝default_dircolors至 ~/, 例如/root, /home/jobs/目錄, 重命名爲.dircolors. 修改文件中STICKY_OTHER_WRITABLE和OTHER_WRITABLE的數值:
        STICKY_OTHER_WRITABLE 01;34 # dir that is sticky and other-writable (+t,o+w)
        OTHER_WRITABLE 01;34 # dir that is other-writable (o+w) and not sticky    
Note: ~/.dircolors將被~/.bashrc調用.
Src: http://www.cyberciti.biz/tips/where-is-color-of-ls-command-defined.html