官术网_书友最值得收藏!

Using file attributes with conditional logic

Earlier in this book, we touched upon various tests for strings, numbers, and variables. Using a similar concept built into Bash, we can also use various attributes to test against files and directories. This extends upon the introduction conditional logic to perform tests on files. Does an example exist? Is it a directory? and so on.

For a moment, though, couldn't we just use the results from executing and checking the return code? Absolutely! This is another method you can use, especially if you are using a version of Bash that supports all of Bashes features. It is just another way to "skin the rabbit".

Let's start off first with some of the common flags, which return true if:

  • -e: The file exists
  • -f: This is a regular file and not a directory or device file
  • -s: The file is not empty or zero in size
  • -d: This is a directory
  • -r: This has read permissions
  • -w: This has write permissions
  • -x:This has execute permissions
  • -O: This is the owner of the file the current user
  • -G: This executes the user if they have the same group as yours
  • f1 (- nt, -ot, -eff2: Refers to if f1 is newer than f2, older than f2, or are hard-linked to the same file
There is more information available on file test operations in the GNU Bash manual:  https://www.gnu.org/software/bash/manual/html_node/Bash-Conditional-Expressions.html.
主站蜘蛛池模板: 泽州县| 雷波县| 额济纳旗| 宁陵县| 陇西县| 竹山县| 婺源县| 雅江县| 双辽市| 兴城市| 光泽县| 墨玉县| 罗山县| 绥阳县| 桐梓县| 临江市| 灵武市| 华亭县| 武川县| 东乡县| 东兰县| 咸阳市| 高密市| 东港市| 融水| 新和县| 延川县| 阿拉善右旗| 同仁县| 同心县| 湘乡市| 客服| 乐至县| 沙河市| 黄冈市| 三江| 仙居县| 当涂县| 通城县| 方山县| 永仁县|