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Project clarifications

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Remzi Arpaci-Dusseau
2018-02-08 09:34:31 -06:00
parent 98972e54a2
commit 7ae7bae89f
1 changed files with 9 additions and 1 deletions
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processes-shell/README.md
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@@ -115,6 +115,8 @@ consider the `access()` system call. For example, when the user types `ls`,
and path is set to include both `/bin` and `/usr/bin`, try `access("/bin/ls", and path is set to include both `/bin` and `/usr/bin`, try `access("/bin/ls",
X_OK)`. If that fails, try "/usr/bin/ls". If that fails too, it is an error. X_OK)`. If that fails, try "/usr/bin/ls". If that fails too, it is an error.
Your initial shell path should contain one directory: `/bin'
### Built-in Commands ### Built-in Commands
Whenever your shell accepts a command, it should check whether the command is Whenever your shell accepts a command, it should check whether the command is
@@ -138,7 +140,9 @@ supplied by the user; if `chdir` fails, that is also an error.
separated by whitespace from the others. A typical usage would be like this: separated by whitespace from the others. A typical usage would be like this:
`wish> path /bin /usr/bin`, which would add `/bin` and `/usr/bin` to the `wish> path /bin /usr/bin`, which would add `/bin` and `/usr/bin` to the
search path of the shell. If the user sets path to be empty, then the shell search path of the shell. If the user sets path to be empty, then the shell
should not be able to run any programs (except built-in commands). should not be able to run any programs (except built-in commands). The
`path` command always overwrites the old path with the newly specified
path.
### Redirection ### Redirection
@@ -178,6 +182,10 @@ In this case, instead of running `cmd1` and then waiting for it to finish,
your shell should run `cmd1`, `cmd2`, and `cmd3` (each with whatever arguments your shell should run `cmd1`, `cmd2`, and `cmd3` (each with whatever arguments
the user has passed to it). the user has passed to it).
**Important:** For any new processes your shell creates via `fork()`, you must
make sure to use `wait()` (or `waitpid`) to wait for them to complete. Not
doing so is a bug.
### Program Errors ### Program Errors