Linux at command source code

how to read AT commands with c++ code in linux

I wrote the following code in which I am trying to send a message from a SM5100b GSM(which is connected to a Rasberry Pi) to my mobile. It is working but I can check the results of AT commands for example Ok, Ok, +CME ERROR: 4, Ok only when I have Cutecom emulator opened. How can I write a «read» function in this code to give me these results during the compiling line by line? I tried something like out = read(fd, n, sizeof(n)) but I did not have results. I am using Raspian a Debian OS and Codeblocks.

#include /* Standard input/output definitions */ #include /* String function definitions */ #include /* UNIX standard function definitions */ #include /* File control definitions */ #include /* Error number definitions */ #include /* POSIX terminal control definitions */ int open_port(void) < int fd; /* File descriptor for the port */ int n,d,e,f,o,out; fd = open("/dev/ttyAMA0", O_RDWR | O_NOCTTY | O_NDELAY); if (fd == -1) < /* Could not open the port. */ perror("open_port: Unable to open /dev/ttyAMA0"); >else fcntl(fd, F_SETFL, 0); sleep(2); n = write(fd, "AT\r\n", 4); if (n < 0) fputs("write() of 4 bytes failed!\n", stderr); sleep(2); d = write(fd, "AT+CMGF=1\r", 10); if (d < 0) fputs("write() of 10 bytes failed!\n", stderr); sleep(2); e = write(fd, "AT+CMGS=\"6034****\"\r", 20); if (e < 0) fputs("write() of 20 bytes failed!\n", stderr); sleep(2); f = write(fd, "hello\r\x1A", 10); if (f < 0) fputs("write() of 10 bytes failed!\n", stderr); sleep(2); return (fd); >int main(void)

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Linux Code Example Demonstrating the Usage of the ‘at’ Command

In order to schedule a task for 8:00 AM on the upcoming Tuesday, you can execute the command provided below. The output will be displayed as shown in Example3, where the task is scheduled for 8:00 AM on the 15th of April. To confirm if the job has been successfully removed, you can use the atq command. Additionally, you can check the details of the scheduled task by listing them using the atq command.

How can I use an at command in a shell script?

To handle multiple lines of code, you can utilize a ‘HERE-doc’.

Linux at command, Linux at command. Linux at command is used to schedule a task to execute it once at a specified time, without editing a configuration file. It is an alternative to the cron job scheduler. It can be useful if we want to execute a process after some time, such as a shutdown system, taking backups, sending emails as reminders, …

How to read AT commands with c++ code in linux

One option is to create a function named sendAT, which could perform a similar action as follows:

int sendAT(char* command,int fd) < size_t cmdlen = strlen(command); int n = write(fd,command, cmdlen); if (n != cmdlen) return -1 char reply[40]; n = read(fd,reply,sizeof(reply)); reply[n] = 0; //Terminate the string if (strcmp(reply, "OK")==0) return 0; //All went well else return -1; //Some error occurred >

Currently, there exists a significant amount of redundant code that performs identical actions for each command transmitted to the phone.

Whatis command in Linux with Examples, Options: whatis -d: This option prints the debugging information. Example: whatis -d ls. whatis -v: This option will prints verbose warning messages. Example: whatis -v ls. whatis -r : This option interprets each of the name as a regular expression. If any of the names match any part of a page name, a match …

Linux at command

The Linux «at» command is employed to schedule a task for execution at a specified time, without the need to edit a configuration file. It serves as an alternative to the cron job scheduler and proves useful for various actions like initiating a system shutdown, creating backups, sending reminder emails, and more.

The at command has the ability to execute a command or script at a designated time and date, or at a specific interval of time. We have the option to use minutes, hours, days, or weeks to indicate the timing. Additionally, it supports certain keywords like midnight or teatime (referring to ‘to 4 pm’).

Note: It cannot be used for recurring tasks, for recurring tasks prefer the Linux crontab.

The atq and atrm commands are included in the at command, and we will briefly explain both commands.

The atq command is utilized to view the pending tasks of the user. If the user is a root user, it will list all the tasks. However, if the user is not a root user, it will only display the tasks of that specific user. The output is displayed in the following format: Task id, date, hour, queue, and username.

The atrm command is utilized to remove tasks based on their job number.

Options

The ‘at’ command offers several options to enhance its specificity. The following options are available with the at command:

• -V: This function is utilized to exhibit the number for standard errors and exit with a successful status.
• The queue parameter is utilized to indicate the queue, which is denoted by a letter ranging from ‘a’ to ‘z’ or ‘A’ to ‘Z’. The default queue is simply referred to as «queue», while the batch queue is labeled as «b». The priority of the queues increases as the letter designation gets higher. There is a special queue denoted by ‘=’, which is exclusively reserved for the currently active jobs.
• The «-m» option is utilized to notify the user via email upon successful completion of the job, assuming there is no output.
• — M: The purpose of this is to ensure that no mail is ever sent to the user.
• The option «-f» allows for reading the job from a file instead of using the standard output.
• The time to run a job is specified using the -t option, which should be in the format [[CC]YY]MMDDhhmm[.ss].
• The -l option is a synonym for the atq command.
• The -r option is a synonym for the atrm command.
• The -d option serves as a synonym for the atrm command.
• The option -b is synonymous with the batch command.
• The option «-v» is utilized to present the job’s execution time prior to its execution.

In order to utilize the at command, installation on our system is necessary. Now let’s learn the process of installing it.

Install at command in Linux (Ubuntu)

To install the at command, run the following command:

To initiate the process, input the system password when prompted and hit ENTER. This will trigger the installation of the at command to your machine, resulting in the activation of a daemon process. Take note of the output provided below.

After installing the at command, it is necessary to start and enable the atd service. To accomplish this, execute the following commands to ensure that the atd service starts and enables during the boot time.

systemctl start atd systemctl enable atd

Executing the command provided above will initiate and activate the atd service. Please refer to the subsequent output for further information.

After enabling the atd service on our machine, we have the ability to schedule any task or command. With that in place, we can now proceed to scheduling our initial task.

Schedule the first task using at

To schedule a task, simply use the at command and specify either a specific time or a keyword.

To schedule the task of backing up sh at 10.20 pm, simply execute the following command.

at 10.20 pm warning: commands will be executed using /bin/sh at> sh backup.sh at> ^d

To complete the task, you can either press CTRL+D or use the ^d keys. By executing the above command, the backup.sh will be scheduled for 10.20 pm. Please refer to the following output for more details.

For the same process, we can utilize the command provided below.

echo "sh backup.sh" | at 10.20 pm

The mentioned command will execute the backup.sh script at 10.20 pm. Take a look at the following output.

List the scheduled tasks

To view the list of scheduled tasks, the «atq» command can be used. When executed by the root user, it will display all jobs of all users. However, if executed by a non-root user, it will only show the jobs of that specific user. Follow the command syntax below to execute it:

Consider the below output:

Based on the output provided, it is evident that we have scheduled a single task. The output showcases the task id, date and time, as well as the user name.

Remove scheduled task

To delete a scheduled task, use the «atrm» command followed by the task ID. Similarly, to remove a scheduled job, execute the «atrm» command followed by the job ID.

The task with task id 2 will be removed by the command mentioned above. Please refer to the following command:

Upon reviewing the aforementioned output, it becomes apparent that when a job is successfully removed, no output will be displayed. To confirm the successful removal of a job, execute the atq command.

Check the content of the scheduled task

To list the tasks, the atq command can be used. However, to determine which script or command is scheduled, the at command should be executed with the ‘-c’ option followed by the task id. The command can be executed in the following manner:

Executing the command mentioned above will result in the display of the task content with task id 2. «»».

Examples of the at command

Here are a few helpful examples of the at command:

Set a task to be scheduled for 8:00 AM.

Execute the command in the following manner to schedule the task for 8:00 AM.

Schedule a task for 8:00 AM on the upcoming Tuesday.

To set a task for 8:00 AM on the upcoming Tuesday, use the following command for execution:

Schedule a task for April 15th at 8:00 AM.

To set a task for execution on the morning of April 15th at 8:00 AM, use the command provided below.

Set a task to be scheduled tomorrow at 8:00 AM.

Execute the command below to schedule a task tomorrow at 8:00 AM.

Example5: Plan tasks for execution immediately after a 2-hour interval.

To schedule a task for execution in exactly 2 hours, use the following command:

Getting Help

In case you encounter any difficulties while using the ‘at’ command, you can refer to the terminal’s manual for assistance. To view the manual for the ‘at’ command, simply execute the ‘man’ command in the following manner:

The manual can be viewed using the command mentioned above, providing details about the at command and its supported options. Take a look at the following output:

To exit the manual, press the ‘q’ key, and for further reading, scroll through the output.

Linux — How can I use an at command in a shell script?, I am trying to use the Unix at command (for setting a job to run at a certain time) in a shell script. The time will be specified by user input using getopts and optarg which seem to be working fine, the problem is at.How do I write the at command into the script to run at a certain time based on input from the user?. …

Atq command in linux with examples

The command «atq» shows a list of pending jobs scheduled by the user. If the user is the superuser, all pending jobs from all users will be shown. The output includes the job number, date, hour, queue, and username for each job.

• — V: The version number will be shown on standard error and the program will exit successfully.
• The command «-q» is used to show the job of a specified queue. Any single letter from ‘a’ to ‘z’ and ‘A’ to ‘Z’ can denote a queue. By default, the queue ‘a’ is designated for ‘at’, and the queue ‘b’ is designated for ‘batch’. If a job is currently running, its queue name will be indicated with an «=» sign. If a job is submitted to a queue with an uppercase letter, it is treated as if it were submitted to the ‘batch’ queue at the time of the job. To display all pending jobs of a user, the command «atq» without arguments can be used. To display all pending jobs of all users, including the root user, the command «atq» without arguments can be used. To view jobs belonging to a specific queue, use the following command: atq -q [queue_letter] The above command will show all the jobs that belong to the queue ‘a’.

At Command in Linux with Examples, at command is a command-line utility that is used to schedule a command to be executed at a particular time in the future. Jobs created with at command are executed only once. The at command can be used to execute any program or mail at any time in the future. It executes commands at a particular time and accepts times of the form HH:MM to run

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