Changes between Version 17 and Version 18 of cypress/BasicLinuxComands

Timestamp:

08/23/16 16:07:35 (8 years ago)

Author:

cbaribault

Comment:

CEB 20160823 - Added CAUTION for rmdir, cp, mv. Also added commands less, zless, zmore, >, >>, <.

cypress/BasicLinuxComands

@@ -116 +116 @@
 
 == rmdir ==
-Removes directories. The '''rmdir''' is a safer approach than using '''rm -r''' as it will only act on empty directories.
+Removes directories. CAUTION: THERE IS NO UNDOING THIS COMMAND AS WELL.
+
+The '''rmdir''' is a safer approach than using '''rm -r''' as it will only act on empty directories.
 
 {{{
@@ -131 +133 @@
 
 === cp ===
-Copy file to new location.
+Copy file to new location.  CAUTION: THERE IS NO UNDOING THIS COMMAND AS WELL - SEE ALSO OPTIONS '''-i''' and '''-n'''.
 
 In the example below sourcefile already exists, and destinationfile may or may not exist and will become a copy of sourcefile.
@@ -144 +146 @@
 Take note of the order here: source first, destination second. This is the standard order across most *nix commands.
 === mv ===
-Move a file to a new location.
+Move a file to a new location. CAUTION: THERE IS NO UNDOING THIS COMMAND AS WELL - SEE ALSO OPTIONS '''-i''' and '''-n'''.
 {{{
 [tulaneID@cypress1 ~]$ mv file1 file2
@@ -196 +198 @@
 === more ===
 '''more''' is like '''cat''', except it prints the file one page at a time. The spacebar is used to continue on to the next page.
+
+=== less ===
+'''less''' is like '''more''', except it handles large files more efficiently in memory and supports a bit more flexibility in file navigation.
+
+=== zmore, zless ===
+'''zmore''' and '''zless''' are the counterparts of '''more''' and '''less''', respectively, for viewing files (with extension '''.gz''') compressed via '''gzip'''.
+
+(See also '''man gzip'''.)
 
 == Basic Linux Commands Exercise ==
@@ -338 +348 @@
 }}} 
 
+=== I/O Redirection ( >, >> and < ) ===
+
+Redirect input or output. CAUTION: THERE IS NO UNDOING THE REDIRECT OVERWRITE `>` COMMAND.
+
+The redirect output operator, `>`, takes the output (see '''man stdout''') of a command and redirects it to a file. For example we could "redirect" the output of '''grep''' above to  a file in order to capture the results of the above search
+
+{{{
+[tulaneID@cypress1 examples]$ head -5 numbers.txt | grep 1 > grep.out
+[tulaneID@cypress1 examples]$ cat grep.out
+01
+}}}
+
+The redirect append output operator `>>` does the same as `>` except the former APPENDS whereas the latter OVERWRITES the output to the specified file.
+
+The redirect input operator `<` is used for redirecting input
+
+{{{
+[tulaneID@cypress1 examples]$ cat < grep.out
+01
+}}}
+
 === history ===
 Displays the command history list with line numbers. You can add an optional integer, n, argument to display only the last n commands