# RHCSA EX200 - Input/Output Redirection LAB ### Use Input/Output Redirection #### Create a Server Health Log File 1. Create a server health log file that contains a sequential number of outputs with the hostname, date and time, and a simple header: ``` cloud_user@server1: ~ $ { echo " " ; echo "==== `date` on `hostname` ====" ; df -hT ; } ==== Wed May 1 20:53:07 UTC 2024 on server1 ==== Filesystem Type Size Used Avail Use% Mounted on devtmpfs devtmpfs 1.8G 0 1.8G 0% /dev tmpfs tmpfs 1.9G 0 1.9G 0% /dev/shm tmpfs tmpfs 1.9G 17M 1.9G 1% /run tmpfs tmpfs 1.9G 0 1.9G 0% /sys/fs/cgroup /dev/xvda2 xfs 20G 14G 6.7G 67% / tmpfs tmpfs 373M 4.0K 373M 1% /run/user/1001 ``` 2. Rerun the previous command, and output this to a text file: ``` { echo " " ; echo "==== `date` on `hostname` ====" ; df -hT ; } > `hostname`-health.txt ``` 3. Review the output: ```bash cloud_user@server1: ~ $ cat server1-health.txt ==== Wed May 1 20:53:51 UTC 2024 on server1 ==== Filesystem Type Size Used Avail Use% Mounted on devtmpfs devtmpfs 1.8G 0 1.8G 0% /dev tmpfs tmpfs 1.9G 0 1.9G 0% /dev/shm tmpfs tmpfs 1.9G 17M 1.9G 1% /run tmpfs tmpfs 1.9G 0 1.9G 0% /sys/fs/cgroup /dev/xvda2 xfs 20G 14G 6.7G 67% / tmpfs tmpfs 373M 4.0K 373M 1% /run/user/1001 ``` Observe what was added to the file. 4. Rerun the first `echo` command to create the server health log file twice more: ``` { echo " " ; echo "==== `date` on `hostname` ====" ; df -hT ; } > `hostname`-health.txt ``` 5. Review the output using `cat server1-health.txt` again to see how many times the command was run. 6. Change the server health log file to contain a double redirect to ensure that the initial and subsequent outputs are not overwritten: ``` { echo " " ; echo "==== `date` on `hostname` ====" ; df -hT ; } >> `hostname`-health.txt ``` 7. Run the above command 2 more times. 8. Inspect the output again using `cat server1-health.txt`. 9.
cat server1-health.txt cloud\_user@server1: ~ $ cat server1-health.txt ==== Wed May 1 20:58:43 UTC 2024 on server1 ==== Filesystem Type Size Used Avail Use% Mounted on devtmpfs devtmpfs 1.8G 0 1.8G 0% /dev tmpfs tmpfs 1.9G 0 1.9G 0% /dev/shm tmpfs tmpfs 1.9G 17M 1.9G 1% /run tmpfs tmpfs 1.9G 0 1.9G 0% /sys/fs/cgroup /dev/xvda2 xfs 20G 14G 6.7G 67% / tmpfs tmpfs 373M 4.0K 373M 1% /run/user/1001 ==== Wed May 1 21:00:24 UTC 2024 on server1 ==== Filesystem Type Size Used Avail Use% Mounted on devtmpfs devtmpfs 1.8G 0 1.8G 0% /dev tmpfs tmpfs 1.9G 0 1.9G 0% /dev/shm tmpfs tmpfs 1.9G 17M 1.9G 1% /run tmpfs tmpfs 1.9G 0 1.9G 0% /sys/fs/cgroup /dev/xvda2 xfs 20G 14G 6.7G 67% / tmpfs tmpfs 373M 4.0K 373M 1% /run/user/1001 ==== Wed May 1 21:00:25 UTC 2024 on server1 ==== Filesystem Type Size Used Avail Use% Mounted on devtmpfs devtmpfs 1.8G 0 1.8G 0% /dev tmpfs tmpfs 1.9G 0 1.9G 0% /dev/shm tmpfs tmpfs 1.9G 17M 1.9G 1% /run tmpfs tmpfs 1.9G 0 1.9G 0% /sys/fs/cgroup /dev/xvda2 xfs 20G 14G 6.7G 67% / tmpfs tmpfs 373M 4.0K 373M 1% /run/user/1001
#### Search for Files in the `/home` Directory 1. Find all the files in the `/home` directory owned by the `cloud_user`: ``` find /home -user cloud_user ``` Observe a long list of filenames, along with 2 `Permission denied` errors at the end. 2. Generate clean lines of output without the 2 errors: ``` find /home -user cloud_user 2> /dev/null ``` 3. Find out how many clean lines of output there are: ``` find /home -user cloud_user 2> /dev/null | wc -l ``` 4. Save the output to a text file: ``` find /home -user cloud_user 2> /dev/null > cloud_user-files.txt ``` 5. Ensure the filenames are in the text file: ``` cat cloud_user-files.txt ``` 6. Number the list of filenames, and save them in another text file: ``` nl cloud_user-files.txt > numberedfiles.txt ``` 7. Ensure the numbered filenames are in the text file: ``` cat numberedfiles.txt ``` 8. Sort the numbered lines: ``` sort numberedfiles.txt ``` Observe that because there were no leading zeroes in front of the lower numbers, it doesn't sort properly. 9. To fix this, run a numeric sort: ``` sort -n numberedfiles.txt ``` 10. Generate a list showing the first-level directories inside `/etc`: ``` find /etc -maxdepth 1 ``` Observe the output includes files that go 1 level further than then `/etc` directory. 11. Add on to the previous command to generate a list showing the space used for the first-level directories inside `/etc`: ``` find /etc -maxdepth 1 -iname "*.*" -exec du -sh {} \; ``` Observe the previous list now includes total space usage for each item. 12. Rerun the following command, and sort it by space usage from least to most used: ``` find /etc -maxdepth 1 -iname "*.*" -exec du -sh {} \; | sort -h ``` 13. Rerun the previous command, and this time, output it to `etc-space-usage.txt`: ``` find /etc -maxdepth 1 -iname "*.*" -exec du -sh {} \; | sort -h > etc-space-usage.txt ``` You shouldn't see any output aside from 2 directory errors. 14. Review the file: ``` less etc-space-usage.txt ``` Observe the files listed and sorted by space usage. ### Use `grep` and Regular Expressions to Analyze Text 1. Find all the files owned by the `cloud_user` in the `/home` directory: ``` find /home -user cloud_user ``` 2. Find all the files owned by the `cloud_user` in the `/home` directory that contain the word "file": ``` cloud_user@server1: ~ $ find /home -user cloud_user | grep -i file /home/cloud_user/.bash_profile find: ‘/home/ssm-user’/home/cloud_user/numberedfiles.txt /home/cloud_user/cloud_user-files.txt : Permission denied find: ‘/home/devops’: Permission denied ``` Notice in the output that it only searches for the word "file" in the actual filenames rather than within the contents of the file. 3. Use the `-exec` feature of `find` to find the word "file" in the files themselves: ``` find /home -user cloud_user -exec grep -i file {} \; ``` 4. Find out how many lines of output were found: ``` find /home -user cloud_user -exec grep -i file {} \; | wc -l ``` You should see `140` lines at the bottom of the output. 5. Count how many lines were generated without errors: ``` find /home -user cloud_user -exec grep -i file {} \; 2> /dev/null | wc -l ``` You should again see `140` lines. Note that this counts only the standard out rather than the standard error. 6. Utilize the `grep` command directly to find the word "file" inside all files owned by `cloud_user` in the `/home` directory: ``` grep -ir file /usr/share/doc/zip ``` 7. Add a total count of the output to the bottom of the list: ``` grep -ir file /usr/share/doc/zip ; !! | wc -l ``` You should see `965` at the bottom. 8. Run a case-sensitive search for only the word "file" as lowercase: ``` grep -ir file /usr/share/doc/zip ; grep -r file /usr/share/doc/zip | wc -l ``` You should see `925` at the bottom. 9. Create a text file containing all the search results for the word "file": ``` grep -ir file /usr/share/doc/zip ; grep -r file /usr/share/doc/zip > grepoutput.txt ``` 10. Check the text file output: ``` cat grepoutput.txt ```