Software Development Degree BTB520 Lecture Notes - Lecture 4: Bzip2, .Tz, Gzip
31 Oct 2016
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Document Summary
Permissions can only be changed by file owner or superuser (system administrator) Chmod is used to alter access permissions to an existing file or directory the 9 permission bits displayed in an ls -al listing are read/write/execute for user(owner)/group/other. Xxx is 3 octal digits representing the binary string rwxrwxrwx where the first three characters are read/write/execute permission for the user, the next three for the user"s group, and the last three for all others. U represents user, could also be g for group, o for other, a for all. + represents addition of permission, could also be - for removal, = for set. R represents read permission, could also be w for write, x for execute. Eg. chmod u+x file1 - would give the user execute permission in addition to whatever he had before. Eg. chmod g-w file1 - would take away write permission from the user"s group if they had it before.
