access()
Used to check the accessibility of files
int
Access(pathname, access_mode)
Char* pathname;
int access-mode;
The access modes are.
04 read
02 write
01 execute (search)
00 checks existence of a file
& operator
execute a command as a background process.
banner
prints the specified string in large letters. Each argument may be upto 10 characters long.
break
is used to break out of a loop. It does not exit from the program.
Cal
Produces a calender of the current month as standard output. The month (1-12) and year (1-9999) must be specified in full numeric format.
Cal [[ month] year]
Calendar
Displays contents of the calendar file
case operator
The case operator is used to validate multiple conditions.
Case $string in
Pattern 1)
Command list;;
Command list;;
Pattern 3)
Command list;;
easc
cat
(for concatenate) command is used to display the contents of a file. Used without arguments it takes input from standard input
cat [filename(s)]
cat > [filename]
Data can be appended to a file using >>
Some of the available options are :
Cat [-options] filename(S)
-s silent about files that
cannot be accessed
-v enables display of non printinging characters (except tabs, new lines, form-
feeds)
-t when used with –v, it causes tabs to be printed as ^I’s
-e when used with –v, it causes $ to be printed at the end of each line
The –t and –e options are ignored if the –v options is not specified.
cd
Used to change directories
chgrp
Changes the group that owns a file.
Chgrp [grou –id] [filename]
chmod
Allows file permissions to be changed for each user. File permissions can be changed only by the owner (s).
Chmod [+/-][rwx] [ugo] [filename]
chown
Used to change the owner of a file.
The command takes a file(s) as source files and the login id of another user as the target.
Chown [user-id] [filename]
cmp
The cmp command compares two files (text or binary) byte-by-byte and displays the first occurrence where the files differ.
Cmp [filename1] [filename2] -1 gives a long listing
comm.
The comm command compares two sorted files and displays the instances that are common. The display is separated into 3 columns.
Comm. filename1 filename2
first displays what occurs in first files but not in the second
second displays what occurs in second file but not in first
third displays what is common in both files
continue statement
The rest of the commands in the loop are ignored. It moves out of the loop and moves on the next cycle.
cp
The cp (copy) command is used to copy a file.
Cp [filename1] [filename2]
cpio(copy input/output)
Utility program used to take backups.
Cpio operates in three modes:
-o output
-i input
-p pass
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