Deepak Prasad

Bash script arguments and bash script parameters with $0–$9, $#, "$@", shift, and a while/case example; missing-flag values, $# checks, and links to getopts and forwarding all args.

Bash check if file exists with [[ -f ]], test -e, and [ ]; bash if file exists patterns with if/else; symlinks and broken links; check if file exists on Linux with find and stat; quoting, exit codes, and pitfalls.

Bashrc vs bash_profile and profile vs bashrc: when Bash reads ~/.bashrc, ~/.bash_profile, and ~/.profile on login and new terminals, Debian vs Red Hat patterns, and what /etc/skel ships for new users.

Bash until vs while using exit status: bash until loop runs while a command fails, while loop bash runs while it succeeds. Examples for counters, wait until ready, and while read line-by-line.

Bash multiple arguments with positional parameters, bash pass all arguments via "$@", bash pass multiple arguments to a function, forwarding to another script, and bash pass function over SSH with typeset -f or declare …

Bash increment variable and bash add 1 to variable with $(( )), ((++)), bash increment variable in loop (for/while), bash increment counter patterns, let, and post vs pre-increment pitfalls.

Bash if else and bash if then else with elif chains, if else in bash shell scripts, combining conditions, nested if, exit-status semantics, and [[ ]] vs [ ] with links to string and number comparisons.

Bash getopts tutorial: optstring, OPTARG, OPTIND, opterr, bash getopts leading colon behavior for missing option arguments vs invalid options, bash getopts example scripts, shift after parsing, and getopt bash vs getopts …

Bash define function with name() or function keyword, bash function example calls, bash script function arguments ($1, $@), local vs global variables, return exit codes, and capturing output.

Bash for loop and for loop in bash: iterate words, arrays with "${a[@]}", C-style for ((i=0;i

Bash concatenate strings and bash string concat with ${a}${b}, bash append to string using +=, join strings with separators, brace pitfalls (${var}_), loops, newlines, and printf-based joining.

Bash string comparison with == and !=, bash if string equals patterns, compare strings in bash using [[ ]] and [ ], ASCII order, empty (-z) and non-empty (-n) checks, quoting, case folding, and =~ regex.

Bash compare numbers and integers with -eq, -lt, -gt, bash compare variable to number in [[ ]] and (( )), bash if numeric comparison patterns, test, loops, and pitfalls (leading zeros, floats, string vs numeric).

Bash format number with commas using printf thousands grouping, LC_NUMERIC and GNU numfmt, plus a pure Bash comma formatter for integers and decimals. Covers locale (en_US vs en_IN), C/POSIX limits, and readable output …

Nested loops in Java: nested for, while, and do-while (including mixed loops), Scanner menu example, labeled break, and complexity. Runnable examples with OpenJDK 17-tested output.

Learn how to reset index in pandas on a DataFrame or Series. Covers pandas groupby reset_index, reset index to start at 0 with drop=True, dataframe reset_index after sort or filter, df reset_index, and resetting column …

Learn how to check sudo access in Linux. Check if you or another user has sudo privileges with sudo -l, test sudo access non-interactively in a bash script with sudo -n, and list all sudo users, with real tested output.

Learn how to check disk space in Linux from the command line. Use df to check free space, du to check disk usage by folder, and find what is eating your storage, with real tested output and fixes for "No space left on …

Learn how to use git remote set-url to change a remote repository URL. Change origin from HTTPS to SSH, add or delete push URLs, rename remotes, and fix the "this repository moved" error, with real tested examples and …

Learn how to use git push force safely. Understand git push --force vs --force-with-lease, force push to a remote branch, origin master, and after rebase or amend with real examples.

Understand CPU, processor, socket, core, thread, hyper-threading, CPU cache, frequency scaling and Linux commands like lscpu, nproc, mpstat and cpupower with validated output.

Learn how to check filesystem type in Linux for mounted paths, disks, partitions, LVM volumes, USB drives, ISO media, and unmounted filesystem images with tested findmnt, lsblk, blkid, df, file, stat, udevadm, fstab, …

Learn how to refresh network settings in Ubuntu after IP address, route, DNS, DHCP, Netplan, NetworkManager, or systemd-networkd changes. Includes safe remote-server workflow, tested verification commands, and practical …

Learn how to configure a VNC server on Ubuntu with TigerVNC, XFCE, a per-user VNC password, localhost-only binding, SSH tunneling, firewall checks, and a systemd service for persistent remote desktop access.

Learn what systemd is in Linux and how to use systemctl to check system state, list services, inspect units, view targets, read logs, verify unit files, and test transient services with practical tested examples.

Learn how to check Linux kernel version with tested uname, hostnamectl, procfs, journalctl, dmesg, boot image, dpkg, and apt commands, and understand the difference between the running kernel and installed kernel …

Learn how to list disks in Linux and check disk type, HDD or SSD status, transport interface, model, serial number, partition table, and filesystem details with tested lsblk, sysfs, udevadm, lspci, lshw, fdisk, parted, …

Tested Linux commands to check thread count per process using proc task directories, proc status, ps NLWP/LWP, ps -T, top -H and pstree, plus system thread limits.

Tested Linux commands to show hidden files with ls, list only hidden files, find hidden files recursively, and check hidden file or directory size with du.

commands to copy file from one server to another in Linux or Unix with examples using sftp scp rsync sshfs nfs. copy using shell script between two machine