13. 1.Wirte command write -Send a message to another user Syntax: write user [ttyname] Example $ Write maude This is a test message <CTRL-D>
14. 2.Xargs command Execute a command, passing constructed argument list(s). The arguments are typically a long list of filenames (generated by ls or find) that are passed to xargs via a pipe. Syntax: xargs [options] [command]
15. 3.Yes command `yes' prints the command line arguments, separated by spaces and followed by a newline, forever until it is killed. If no arguments are given, it prints `y' followed by a newline forever until killed. The only options are a lone `--help' or `--version'.
16. 4.whoami command Print the current user id and name. Syntax: whoami [options] Options whoami produces the same result as the id -un command
17. Alias -Create an alias Syntax alias [-p] [name[=value] ...] unalias [-a] [name ... ] 5.Alias command
20. 8.basename command Strip directory and suffix from filenames Syntax: basename NAME [SUFFIX] basename OPTION
21. 9.cat command Display the contents of a file (concatenate) Syntax: cat [Options] [File]...
22. 10.Cd command Change Directory - change the current working directory to a specific Folder. Syntax : cd [Options] [Directory]
23. 11.cfdisk command Curses based disk partition table manipulator for Linux Syntax: cfdisk [ -agvz ] [ -c cylinders ] [ -h heads ] [ -s sectors-per-track ] [ -P opt ] [ device ]
24. 12.chgrp command Change group ownership 'chgrp' changes the group ownership of each given File to Group (which can be either a group name or a numeric group id) or to the group of an existing reference file. Syntax: chgrp [Options]... {Group | --reference=File} File...
26. 14.chkconfig command Update and query runlevel information for system services. Syntax: chkconfig --list [name] chkconfig --add name chkconfig --del name chkconfig [--level levels] name <on|off|reset> chkconfig [--level levels] name
27. 15.cksum command Print CRC checksum and byte counts Computes a cyclic redundancy check (CRC) checksum for each given File, or standard input if none are given or for a File of - Syntax cksum [Option]... [File]...
28. 16.cmp command Compare two files, and if they differ, tells the first byte and line number where they differ. You can use the `cmp' command to show the offsets and line numbers where two files differ. `cmp' can also show all the characters that differ between the two files, side by side. Syntax cmp options... FromFile [ToFile]
29. 17.comm command Common - compare two sorted files line by line Syntax: comm [options]... File1 File2
30. 18.command Run command with arguments ignoring any shell function named command. SYNTAX command [-pVv] command [arguments ...]
31. 19.continue command Resume the next iteration of an enclosing for, while, until, or select loop. SYNTAX: continue [n] If n is supplied, the execution of the nth enclosing loop is resumed. n must be greater than or equal to 1. The return status is zero unless n is not greater than or equal to 1.
32. 20.Cp command Copy one or more files to another location Copy SOURCE to DEST, or multiple SOURCE(s) to DIRECTORY. Syntax: cp [options]... Source Dest cp [options]... Source... Directory
33. 21.cron command daemon to execute scheduled commands Syntax: cron Cron should be started from /etc/rc or /etc/rc.local. It will return immediately
34. 22.csplit command Split a file into context-determined pieces. SYNTAX csplit [options]... INPUT PATTERN... Creates zero or more output files containing sections of INPUT (standard input if INPUT is `-')
35. 23.cut command Divide a file into several parts (columns) Writes to standard output selected parts of each line of each input file, or standard input if no files are given or for a file name of `-'. Syntax cut [OPTION]... [FILE]..
36. 24.date command Display or change the date. Syntax date [option]... [+Format] date [option] [MMDDhhmm[[CC]YY][.ss]] `date' with no arguments prints the current time and date
38. 26.DD command Convert and copy a file, write disk headers, boot records, create a boot floppy. dd can make an exact clone of an (unmounted) disk. Syntax dd [Options]
39. 27.dd rescue command Data recovery tool, save data from a crashed partition. Syntax ddrescue [options] infile outfile [logfile]
40. 28.declare command Declare variables and give them attributes. SYNTAX declare [-afFrxi] [-p] [name[=value]]
41. 29.df command Disk Free - display free disk space. With no arguments, `df' reports the space used and available on all currently mounted filesystems. SYNTAX df [option]... [file]...
42. 30.diff command Display the differences between two files, or each corresponding file in two directories. Each set of differences is called a "diff" or "patch". Syntax diff [options] from-file to-file
43. 31.dircolors command Color setup for `ls', outputs a sequence of shell commands to set up the terminal for color output from `ls' (and `dir', etc.). Syntax eval `dircolors [options]... [file]`
44. 32.yes command `yes' prints the command line arguments, separated by spaces and followed by a newline, forever until it is killed. If no arguments are given, it prints `y' followed by a newline forever until killed. The only options are a lone `--help' or `--version'.
45. 33.watch command Execute a program periodically, showing output full screen Syntax watch [options] command command_options
46. 34.wc command Print byte, word, and line counts, count the number of bytes, whitespace-separated words, and newlines in each given FILE, or standard input if none are given or for a FILE of `-'. Syntax wc [options]... [file]...
48. 36.screencommand Multiplex a physical terminal between several processes (typically interactive shells). Syntax: Start a screen session: screen [ -options ] [ cmd [args] ] Resume a detached screen session: screen -r [[pid.]tty[.host]] screen -r sessionowner/[[pid.]tty[.host]]
49. 37.diff command Merge two files interactively. (Show differences) with output to outfile. SYNTAX sdiff -o outfile [options] from-file to-file
50. 38.select command select construct allows the easy generation of menus. It has almost the same syntax as the for command. Syntax select name [in words ...]; do commands; done
51. 39.seq command Print a sequence of numbers to standard output Syntax: seq [options]... [FIRST [STEP]] LAST...
52. 40.set command Manipulate shell variables and functions. Syntax: set [--abBCefhHkmnpPtuvx] [-o option] [argument ...]
54. 42.hash command Remember the full pathnames of commands specified as name arguments, so they need not be searched for on subsequent invocations. SYNTAX hash [-r] [-p filename] [name]
55. 43.id command Print real and effective user id (uid) and group id (gid), prints identity information about the given user, or if no user is specified the current process. SYNTAX id [options]... [username]
56. 44.fup / ifdown command Bring a network interface up or down Syntax ifup [options] -a | IFACE... ifdown [options] -a|IFACE...
57. 45.less command Display output one screen at a time, Search through output, Edit the command line. SYNTAX: less [options] <command> | less [options]
58. 46.let command Perform arithmetic on shell variables. Syntax let expression [expression] Each expression is an arithmetic expression to be evaluated. If the last expression evaluates to 0, let returns 1; otherwise 0 is returned.
59. 47.bc command An arbitrary precision calculator language Syntax: bc options file...
61. 49.break command Exit from a for, while, until, or select loop SYNTAX: break [n] If n is supplied, the nth enclosing loop is exited. n must be greater than or equal to 1
62. 50.bulitin command Run a shell builtin, passing it args, and return its exit status. SYNTAX: builtin [shell-builtin [args]] This is useful when defining a shell function with the same name as a shell builtin, retaining the functionality of the builtin within the function
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