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$ /lib/ld-linux.so.2
is the runtime linker/loader for ELF binaries on Linux.
=(cmd) is a zsh trick to take the output for the command "inside" it and save it to a temporary file.
$ echo -e 'blah' | gcc -x c -o /dev/stdout -
pipes the C source to gcc. -x c tells gcc that it's compiling C (which is required if it's reading from a pipe). -o /dev/stdout - tells it to write the binary to standard output and read the source from standard input.
because of the the =() thing, the compiled output is stashed in a tempfile, which the loader then runs and executes, and the shell tosses the tempfile away immediately after running it.
When dealing with system resource limits like max number of processes and open files per user, it can be hard to tell exactly what's happening. The /etc/security/limits.conf file defines the ceiling for the values, but not what they currently are, while
$ ulimit -a
will show you the current values for your shell, and you can set them for new logins in /etc/profile and/or ~/.bashrc with a command like:
$ ulimit -S -n 100000 >/dev/null 2>&1
But with the variability in when those files get read (login vs any shell startup, interactive vs non-interactive) it can be difficult to know for sure what values apply to processes that are currently running, like database or app servers. Just find the PID via "ps aux | grep programname", then look at that PID's "limits" file in /proc. Then you'll know for sure what actually applies to that process.
You might want to secure your AWS operations requiring to use a MFA token. But then to use API or tools, you need to pass credentials generated with a MFA token.
This commands asks you for the MFA code and retrieves these credentials using AWS Cli. To print the exports, you can use:
`awk '{ print "export AWS_ACCESS_KEY_ID=\"" $1 "\"\n" "export AWS_SECRET_ACCESS_KEY=\"" $2 "\"\n" "export AWS_SESSION_TOKEN=\"" $3 "\"" }'`
You must adapt the command line to include:
* $MFA_IDis ARN of the virtual MFA or serial number of the physical one
* TTL for the credentials
Similar to `cpulimit`, although `prlimit` can be found shipped with recent util-linux.
Example: limit CPU consumption to 10% for a math problem which ordinarily takes up 100% CPU:
Before:
$ bc -l
swap out "80" for your port of interest. Can use port number or named ports e.g. "http"
swap out "80" for your port of interest. Can use port number or named ports e.g. "http"
Replace 'csv_file.csv' with your filename.
Substitute for #11720
Can probably be even shorter and easier.
