Differences

This shows you the differences between two versions of the page.

--- bash [2012/01/27 15:59]
k2patel [Bash]
+++ bash [2020/08/10 02:35]
@@ Line 1: / Line 1: @@
-====== Bash ======
- [[ Floating Point Calculation ]]
-==== Bash Short-Cut ====
-=== CTRL Key Bound ===
-<code bash>
-Ctrl + a - Jump to the start of the line
-Ctrl + b - Move back a char
-Ctrl + c - Terminate the command
-Ctrl + d - Delete from under the cursor
-Ctrl + e - Jump to the end of the line
-Ctrl + f - Move forward a char
-Ctrl + k - Delete to EOL
-Ctrl + l - Clear the screen
-Ctrl + r - Search the history backwards
-Ctrl + R - Search the history backwards with multi occurrence
-Ctrl + u - Delete from the cursor to the beginning of the line.
-Ctrl + w - Delete from the cursor to the start of the word.
-Ctrl + xx - Move between EOL and current cursor position
-Ctrl + x @ - Show possible hostname completions
-Ctrl + x Ctrl + u - Undo the last changes. Ctrl-_ does the same
-Ctrl + y - Pastes text from the clipboard.
-Ctrl + z - Suspend/ Stop the command
-Ctrl + ] x - Where x is any character, moves the cursor forward to the next occurance of x.
-</code>
-=== ALT Key Bound ===
-<code bash>
-Alt + < - Move to the first line in the history
-Alt + > - Move to the last line in the history
-Alt + ? - Show current completion list
-Alt + * - Insert all possible completions
-Alt + / - Attempt to complete filename
-Alt + . - Yank last argument to previous command
-Alt + b - Move backward
-Alt + c - Capitalize the word
-Alt + d - Delete word
-Alt + f - Move forward
-Alt + l - Make word lowercase
-Alt + n - Search the history forwards non-incremental
-Alt + p - Search the history backwards non-incremental
-Alt + r - Recall command
-Alt + t - Move words around
-Alt + u - Make word uppercase
-Alt + back-space - Delete backward from cursor
-Alt + Ctrl + e	 Expand command line.
-Alt + Ctrl + ] x	 Where x is any character, moves the cursor backwards to the previous occurance of x.
-</code>
-=== More Special Keybindings ===
-Here "2T" means Press TAB twice
-<code bash>
-$ 2T - All available commands(common)
-$ (string)2T - All available commands starting with (string)
-$ /2T - Entire directory structure including Hidden one
-$ 2T - Only Sub Dirs inside including Hidden one
-$ *2T - Only Sub Dirs inside without Hidden one
-$ ~2T - All Present Users on system from "/etc/passwd"
-$ $2T - All Sys variables
-$ @2T - Entries from "/etc/hosts"
-$ =2T - Output like ls or dir
-Esc-Del	 Delete previous word (may not work, instead try Esc followed by Backspace)
-!! - run last command
-!blah – run the most recent command that starts with ‘blah’ (e.g. !ls)
-!blah:p – print out the command that !blah would run (also adds it as the latest command in the command history)
-!$ – the last word of the previous command (same as Alt + .)
-!$:p – print out the word that !$ would substitute
-!* – the previous command except for the last word (e.g. if you type ‘find some_file.txt /‘, then !* would give you ‘find some_file.txt‘)
-!*:p – print out what !* would substitute
-!n	 Execute nth command in history
-!^	 First argument of last command
-^abc^xyz	 Replace first occurance of abc with xyz in last command and execute it
-</code>
-==== Indirect Referance ====
-This is what i come across while writing some simple bash script.\\
-But it seems really usefull. so i am just adding here.\\
-<code bash | Example>
-for inst in instance{1..10}
-do
-	eval var1=\$$inst  ## to evaluate $inst in assignment you have to use \$$inst
-	arry=($var1)
-done
-</code>
-[[http://tldp.org/LDP/abs/html/ivr.html|Source]]
-==== If File Comparision ====
-<code bash>
-[ -a FILE ]	True if FILE exists.
-[ -b FILE ]	True if FILE exists and is a block-special file.
-[ -c FILE ]	True if FILE exists and is a character-special file.
-[ -d FILE ]	True if FILE exists and is a directory.
-[ -e FILE ]	True if FILE exists.
-[ -f FILE ]	True if FILE exists and is a regular file.
-[ -g FILE ]	True if FILE exists and its SGID bit is set.
-[ -h FILE ]	True if FILE exists and is a symbolic link.
-[ -k FILE ]	True if FILE exists and its sticky bit is set.
-[ -p FILE ]	True if FILE exists and is a named pipe (FIFO).
-[ -r FILE ]	True if FILE exists and is readable.
-[ -s FILE ]	True if FILE exists and has a size greater than zero.
-[ -t FD ]	True if file descriptor FD is open and refers to a terminal.
-[ -u FILE ]	True if FILE exists and its SUID (set user ID) bit is set.
-[ -w FILE ]	True if FILE exists and is writable.
-[ -x FILE ]	True if FILE exists and is executable.
-[ -O FILE ]	True if FILE exists and is owned by the effective user ID.
-[ -G FILE ]	True if FILE exists and is owned by the effective group ID.
-[ -L FILE ]	True if FILE exists and is a symbolic link.
-[ -N FILE ]	True if FILE exists and has been modified since it was last read.
-[ -S FILE ]	True if FILE exists and is a socket.
-[ FILE1 -nt FILE2 ]	True if FILE1 has been changed more recently than FILE2, or if FILE1 exists and FILE2 does not.
-[ FILE1 -ot FILE2 ]	True if FILE1 is older than FILE2, or is FILE2 exists and FILE1 does not.
-[ FILE1 -ef FILE2 ]	True if FILE1 and FILE2 refer to the same device and inode numbers.
-[ -o OPTIONNAME ]	True if shell option "OPTIONNAME" is enabled.
-[ -z STRING ]	True of the length if "STRING" is zero.
-[ -n STRING ] or [ STRING ]	True if the length of "STRING" is non-zero.
-[ STRING1 == STRING2 ]	True if the strings are equal. "=" may be used instead of "==" for strict POSIX compliance.
-[ STRING1 != STRING2 ]	True if the strings are not equal.
-[ STRING1 < STRING2 ]	True if "STRING1" sorts before "STRING2" lexicographically in the current locale.
-[ STRING1 > STRING2 ]	True if "STRING1" sorts after "STRING2" lexicographically in the current locale.
-[ ARG1 OP ARG2 ]	"OP" is one of -eq, -ne, -lt, -le, -gt or -ge. These arithmetic binary operators return true if "ARG1" is equal to,
-                        not equal to, less than, less than or equal to, greater than,
-                        or greater than or equal to "ARG2", respectively. "ARG1" and "ARG2" are integers.
-</code>
-==== I/O Redirection ====
-<code text>
-    COMMAND_OUTPUT >
-       # Redirect stdout to a file.
-       # Creates the file if not present, otherwise overwrites it.
-
-       ls -lR > dir-tree.list
-       # Creates a file containing a listing of the directory tree.
-
-    : > filename
-       # The > truncates file "filename" to zero length.
-       # If file not present, creates zero-length file (same effect as 'touch').
-       # The : serves as a dummy placeholder, producing no output.
-
-    > filename
-       # The > truncates file "filename" to zero length.
-       # If file not present, creates zero-length file (same effect as 'touch').
-       # (Same result as ": >", above, but this does not work with some shells.)
-
-    COMMAND_OUTPUT >>
-       # Redirect stdout to a file.
-       # Creates the file if not present, otherwise appends to it.
-
-
-       # Single-line redirection commands (affect only the line they are on):
-       # --------------------------------------------------------------------
-
-    1>filename
-       # Redirect stdout to file "filename".
-    1>>filename
-       # Redirect and append stdout to file "filename".
-    2>filename
-       # Redirect stderr to file "filename".
-    2>>filename
-       # Redirect and append stderr to file "filename".
-    &>filename
-       # Redirect both stdout and stderr to file "filename".
-
-       #==============================================================================
-       # Redirecting stdout, one line at a time.
-       LOGFILE=script.log
-
-       echo "This statement is sent to the log file, \"$LOGFILE\"." 1>$LOGFILE
-       echo "This statement is appended to \"$LOGFILE\"." 1>>$LOGFILE
-       echo "This statement is also appended to \"$LOGFILE\"." 1>>$LOGFILE
-       echo "This statement is echoed to stdout, and will not appear in \"$LOGFILE\"."
-       # These redirection commands automatically "reset" after each line.
-
-
-
-       # Redirecting stderr, one line at a time.
-       ERRORFILE=script.errors
-
-       bad_command1 2>$ERRORFILE       #  Error message sent to $ERRORFILE.
-       bad_command2 2>>$ERRORFILE      #  Error message appended to $ERRORFILE.
-       bad_command3                    #  Error message echoed to stderr,
-                                       #+ and does not appear in $ERRORFILE.
-       # These redirection commands also automatically "reset" after each line.
-       #==============================================================================
-
-
-
-    2>&1
-       # Redirects stderr to stdout.
-       # Error messages get sent to same place as standard output.
-
-    i>&j
-       # Redirects file descriptor i to j.
-       # All output of file pointed to by i gets sent to file pointed to by j.
-
-    >&j
-       # Redirects, by default, file descriptor 1 (stdout) to j.
-       # All stdout gets sent to file pointed to by j.
-
-    0< FILENAME
-     < FILENAME
-       # Accept input from a file.
-       # Companion command to ">", and often used in combination with it.
-       #
-       # grep search-word <filename
-
-
-    [j]<>filename
-       # Open file "filename" for reading and writing, and assign file descriptor "j" to it.
-       # If "filename" does not exist, create it.
-       # If file descriptor "j" is not specified, default to fd 0, stdin.
-       #
-       # An application of this is writing at a specified place in a file.
-       echo 1234567890 > File    # Write string to "File".
-       exec 3<> File             # Open "File" and assign fd 3 to it.
-       read -n 4 <&3             # Read only 4 characters.
-       echo -n . >&3             # Write a decimal point there.
-       exec 3>&-                 # Close fd 3.
-       cat File                  # ==> 1234.67890
-       # Random access, by golly.
-
-
-
-    |
-       # Pipe.
-       # General purpose process and command chaining tool.
-       # Similar to ">", but more general in effect.
-       # Useful for chaining commands, scripts, files, and programs together.
-       cat *.txt | sort | uniq > result-file
-       # Sorts the output of all the .txt files and deletes duplicate lines,
-       # finally saves results to "result-file".
-</code>
- Ref : [[http://www.faqs.org/docs/abs/HTML/io-redirection.html | Faqs ]]
-==== Bash IRC Log ====
-<code bash>
-f(){ local first=$1 second=$2; shift; shift; echo "now, first arg is: $1, second arg is: $2, ... previously, \$1
-                    was: $first and \$2 was: $second"; }; f foo bar baz qux
-</code>
-<code bash>
-{ local -l reply; read -p "$1 [Y/n] " reply; [[ -z $reply || $reply = y?(es) ]]; }
-</code>
-<code bash>
-cd src && find . -depth -type f -exec rm -f /path1/{} \; -o -type d -exec rmdir /path1/{} \;
-</code>
-<code bash>
-gobackto() { local p="$PWD"; while [[ $p ]]; do if [[ ${p##*/} = "$1" ]]; then cd "$p"; return; fi; p=${p%/*}; done; return 1; }
-</code>
-==== Convert String to Array ====
-It's simple and easy to convert string to array
-<code bash>
-$var1="testing is simple"
-arry=($var1)
-echo ${arry[1]}
-</code>
-==== Networked Info ====
-   * [[ Can we Hide Code ]]
-==== Bash FAQ ====
-  * [[ http://mywiki.wooledge.org/BashFAQ/100 | How do I do string manipulations in bash? ]]
-  * [[ http://mywiki.wooledge.org/BashFAQ/030 | How can I rename ]]
-  * [[ http://mywiki.wooledge.org/BashFAQ/001 | How can i Read File ]]
-  * [[ http://mywiki.wooledge.org/BashFAQ/079 | How can I grep for lines containing foo AND bar, foo OR bar?  Or for files containing foo AND bar, possibly on separate lines? ]]

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