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: 桓仁| 平定县| 福建省| 贵港市| 普陀区| 吴桥县| 博客| 天津市| 乌兰察布市| 永康市| 双桥区| 会理县| 长春市| 唐河县| 大宁县| 西畴县| 彭山县| 武胜县| 石棉县| 桂平市| 大埔区| 北流市| 丰台区| 宝应县| 安新县| 民权县| 光泽县| 遂川县| 即墨市| 江源县| 增城市| 漠河县| 应城市| 龙胜| 边坝县| 深州市| 大荔县| 格尔木市| 长垣县| 南川市| 郓城县|