Master Linux Commands: Compression, Process & Network Management Essentials

1. Compression Management

bunzip2

Function: Decompress .bz2 files. Syntax: bunzip2 [-fkLsvV] [.bz2 file]. It is a symlink to bzip2 -d. Options include -f (force overwrite), -k (keep original), -s (use less memory), -v (verbose), and version/license flags.

bzip2

Function: Compress files into .bz2 format. Syntax:

bzip2 [-cdfhkLstvVz] [--repetitive-best] [--repetitive-fast] [-compression-level] [files]

. It uses a newer algorithm than LZ77/LZ78. Important options: -c (stdout), -d (decompress), -f (force), -h (help), -k (keep), -s (small memory), -t (test), -v (verbose), -L (license), -V (version), and repetitive options for better compression on repeated data.

cpio

Function: Create and restore backup archives. Syntax examples:

cpio [-0aABckLovV] [-C <size>] [-F <archive>] [-H <format>] [-O <archive>] [--block-size=<size>] [--force-local] [--help] [--quiet] [--version]

and other variants. Options include -0 (null), -a (reset access time), -A (append), -b (swap), -B (block size 5210), -c (old ASCII format), -C (set I/O block size), -d (make directories), -E (pattern file), -f (non‑matching), -F (specify archive file), -H (format), -i (extract), -l (link), -L (dereference), -m (preserve modification time), -M (message), -n (numeric uid/gid), -p (pass‑through), -r (rename), -s (swap bytes), -S (sparse), -t (list), -u (unconditional), -v (verbose), -V (dot), and block‑size controls.

gunzip

Function: Decompress .gz files (hard link to gzip). Syntax: gunzip [-acfhlLnNqrtvV] [-s <suffix>] [files...]. Options: -a (ASCII mode), -c (stdout), -f (force), -h (help), -l (list info), -L (license), -n (no name), -N (restore name), -q (quiet), -r (recursive), -S (suffix), -t (test), -v (verbose), -V (version).

gzip

Function: Compress files into .gz format. Syntax:

gzip [-acdfhlLnNqrtvV] [-S <suffix>] [-<compression-level>] [files...]

. Options include -a (ASCII), -c (stdout), -d (decompress), -f (force), -h (help), -l (list), -L (license), -n (no name), -N (name), -q (quiet), -r (recursive), -S (suffix), -t (test), -v (verbose), -V (version), and compression level 1‑9 or --best / --fast.

split

Function: Split a file into smaller pieces. Syntax:

split [--help] [--version] [-<lines>] [-b <bytes>] [-C <bytes>] [-l <lines>] [input_file] [output_prefix]

. By default it splits every 1000 lines. Options: -l (lines per file), -b (bytes per file), -C (keep line integrity), --help, --version.

tar

Function: Create and extract archive files. Syntax:

tar [-ABcdgGhiklmMoOpPrRsStuUvwWxzZ] [-b <block-count>] [-C <directory>] [-f <archive>] [-F <script>] ...

. It supports many options for creating, extracting, listing, preserving permissions, handling multi‑volume archives, compression via -z / -j, and more. Key options: -c (create), -x (extract), -t (list), -v (verbose), -f (archive file), -C (change directory), -z (gzip), -j (bzip2), -J (xz), -p (preserve permissions), -k (keep old files), -r (append), -u (update), -A (concatenate), -L (license), -V (version), and many others.

unzip

Function: Extract .zip archives. Syntax:

unzip [-cflptuvz] [-agCjLMnoqsVX] [-P <password>] [zipfile] [files] [-d <dir>] [-x <files>]

. Options: -c (stdout with conversion), -f (update), -l (list), -p (stdout without conversion), -t (test), -u (update and extract), -v (verbose), -z (show comments), -a (ASCII conversion), -b (no conversion), -C (case‑sensitive), -j (ignore paths), -L (lowercase names), -M (pipe to more), -n (no overwrite), -o (overwrite without prompting), -P (password), -q (quiet), -s (replace spaces with underscores), -V (VMS version), -X (preserve UID/GID).

zgrep

Function: Search compressed files with regular expressions, behaving like grep but operating on compressed input. Syntax: zgrep [options] [files]. Options correspond to standard grep flags.

zip

Function: Create .zip archives. Syntax:

zip [-options] [-b <work-dir>] [-ll] [-n <suffix>] [-t <date>] [-<level>] <zipfile> [files...] [-i <pattern>] [-x <pattern>]

. Important options: -A (adjust auto‑extract), -b (work directory), -c (add comment), -d (delete), -D (no directories), -f (force update), -F (fix), -g (append), -h (help), -i (include pattern), -j (no directories), -J (remove leading data), -k (MS‑DOS names), -l (LF to CRLF), -ll (LF+CR to LF), -L (license), -m (move files), -n (exclude suffix), -o (set archive time), -q (quiet), -r (recursive), -S (include system/hidden), -t (set date), -T (test), -u (update), -v (verbose), -V (VMS attributes), -w (VMS version), -x (exclude pattern), -X (no extra attributes), -y (store symlinks), -z (add comment), -$ (store volume name), and compression level 1‑9.

2. Process Management

crontab

Function: Schedule timed tasks. Syntax: crontab [-u <user>] [file] | crontab [-u <user>] [-elr]. The crontab file format is Minute Hour Day Month DayOfWeek Command. Options: -e (edit), -l (list), -r (remove), -u (specify user).

kill

Function: Terminate processes. Syntax: kill [-s <signal>] [pid...] | kill [-l [signal-number]]. Default signal is SIGTERM (15); SIGKILL (9) forces termination. Use ps or jobs to find PIDs. Options: -l (list signals), -s (specify signal).

nohup

Function: Run a command immune to hangups. Syntax: nohup Command [args...] [&]. Output is appended to nohup.out (or $HOME/nohup.out if not writable). Exit codes: 126 (command not executable), 127 (command not found), otherwise the command’s exit status.

ps

Function: Report process status. Syntax: ps [options] [selection]. Common options: -a (all terminals), -A (all processes), -c (CLS and PRI columns), -f (full format), -l (long format), -u (user‑oriented), -x (all processes), -H (tree), -j (jobs format), -o (custom output), -p (by PID), -t (by terminal), -U / -u (by UID), -V (version), -w (wide). Additional long‑form options are also supported.

renice

Function: Change scheduling priority of processes. Syntax: renice [priority] [-g <group>] [-p <pid>] [-u <user>]. Priority range is -20 (highest) to 19 (lowest). Only root can set negative values or affect other users.

top

Function: Real‑time display of running processes. Syntax: top [bciqsS] [d <seconds>] [n <iterations>]. Options: b (batch mode), c (full command line), d (delay), i (ignore idle/zombie), n (iterations), q (quit), s (secure mode), S (cumulative mode).

who

Function: Show who is logged on. Syntax: who [-Himqsw] [--help] [--version] [am i] [logfile]. Options: -H (heading), -i / -u (idle time), -m (same as "am i"), -q (count only), -s (compatibility), -w (show writeable status).

3. Network Management

curl

Function: Transfer data with URLs. Examples:

Read a web page: curl http://www.linuxidc.com Save to file: curl -o page.html http://www.linuxidc.com Use proxy:

curl -x 123.45.67.89:1080 -o page.html http://www.linuxidc.com

Store cookies: curl -D cookie.txt http://example.com Send cookies: curl -b cookie.txt http://example.com Set user‑agent: curl -A "Mozilla/5.0" http://example.com Set referer: curl -e "mail.linuxidc.com" http://example.com Download files: curl -O http://example.com/file.jpg Batch download: curl -O http://host/{001-201}.JPG Custom filenames: curl -o #2_#1.jpg http://host/{001-201}.JPG Resume download: curl -c -O http://example.com/file FTP download: curl -u user:pass ftp://host/path/file FTP upload: curl -T localfile -u user:pass ftp://host/path/ HTTP upload (PUT): curl -T localfile http://host/abc.cgi POST data: curl -d "user=nick&password=12345" http://host/login.cgi POST file:

curl -F upload=@localfile -F nick=go http://host/up_file.cgi

finger

Function: Display user information. Syntax: finger [-lmsp] [user...]. Options: -l (full info), -m (omit real name), -s (short info), -p (omit plan/file).

ftp

Function: Transfer files using FTP protocol. Syntax: ftp [-dignv] host. Options: -d (debug), -i (no interactive prompts), -g (disable filename globbing), -n (no auto‑login), -v (verbose).

ifconfig

Function: Configure network interfaces. Syntax: ifconfig [interface] [options]. Common options: add / del (IPv6 address), down, up, hw (hardware type/address), io_addr, irq, media, mem_start, metric, mtu, netmask, tunnel, -broadcast, -pointopoint, -promisc, and IP address assignment.

ip

Function: Advanced IP routing and device configuration (iproute2). General syntax: ip [options] [object] [command]. Objects include link, addr, route, etc. Examples:

Show links: ip link show or ip -s link show eth0 Set link up/down: ip link set eth0 up, ip link set eth0 down Change MTU: ip link set eth0 mtu 1000 Rename interface: ip link set eth0 name vbird (requires interface down first)

Change MAC: ip link set eth0 address aa:aa:aa:aa:aa:aa Add IP address: ip address add 192.168.50.50/24 dev eth0 label eth0:vbird Delete IP address: ip address del 192.168.50.50/24 dev eth0 Show routes: ip route show Add route: ip route add 192.168.5.0/24 dev eth0 Add gateway route: ip route add 192.168.10.0/24 via 192.168.5.100 dev eth0 Set default gateway: ip route add default via 192.168.1.2 dev eth0 Delete route:

ip route del 192.168.10.0/24

netstat

Function: Network statistics. Syntax: netstat [options]. Common options: -a (all sockets), -c (continuous), -e (extend), -i (interfaces), -l (listening), -n (numeric), -r (routing table), -s (statistics), -t (TCP), -u (UDP), -w (raw), -x (UNIX sockets), --help, --version.

nslookup

Function: Query DNS for hostnames or IP addresses. Syntax: nslookup [hostname|IP]. Interactive mode shows default server and allows queries; exit quits. Useful for testing forward and reverse DNS, MX records, TXT records.

ping

Function: Test reachability of a host using ICMP. Syntax: ping [options] host. Options: -c (count), -i (interval), -I (interface), -l (preload), -n (numeric output), -p (pattern), -q (quiet), -r (bypass routing), -R (record route), -s (packet size), -t (TTL), -v (verbose).

rcp

Function: Remote copy of files or directories. Syntax: rcp [-pr] source target. Options: -p (preserve attributes), -r (recursive).

route

Function: Manually manipulate the kernel routing table. Syntax:

route [-add|-delete] [-net|-host] target [gw gateway] [netmask mask] [dev iface]

. Example:

route add -net 202.96.96.0 -netmask 255.255.255.0 gw 192.168.1.10 dev eth0

.

tcpdump

Function: Capture and display network packets. Syntax: tcpdump [options] [expression]. Important options: -i (interface), -c (packet count), -w (write to file), -r (read from file), -s (snaplen), -n (numeric), -v / -vv (verbosity), -e (link‑layer header), -X (hex+ASCII), -A (ASCII), -t / -tt (timestamps), -F (filter file), -p (no promiscuous mode), -l (line buffered).

telnet

Function: Remote login over TCP. Syntax: telnet [options] host [port]. Options include -8 (8‑bit), -a (auto login), -b (bind address), -c (no .telnetrc), -d (debug), -e (escape character), -f / -F (Kerberos), -k (Kerberos realm), -l (login name), -L (output 8‑bit), -n (record file), -r (rlogin‑like), -S (TOS), -x (encryption), -X (disable auth).

traceroute

Function: Trace the path packets take to a network host. Syntax: traceroute [options] host [packet‑size]. Options: -f (first TTL), -g (gateway list), -i (interface), -m (max TTL), -p (port), -s (source address), -t (TOS), -w (timeout), -n (numeric), -q (queries per hop), -r (bypass routing), -I (use ICMP), -x (checksum), -v (verbose).

For more details, refer to the original source: https://mp.weixin.qq.com/s/Yxd80jt_pXlLbEtBYqpD_g