Linux - File

hidden

Sh - Hidden files

Metadata

See Linux - Stat (File status)

Monitoring the size of a (log) file

Example:

# the program that run
program=unzip
# the log of the progam
logfile='restoreAll.log'
# Don't touch below, the program
count=0
while kill -0 $(pgrep ${program}) 2> /dev/null; do
    count=$(( $count + 1 ))
	size=$(ls -lh ${logfile} | awk '{ print $5 }')
    echo "${count} - Process is running and the log is ${size}"
    sleep 10
done
echo "${count} - Process has exited"

Comparison

cmp --silent $old $new || echo "files are different"
cmp -b $old $new 

See also : diff

Diff

diff file1 file2 | cat -t

where:

• ^M for CR,
• ^I for tab

See also: comparison

Filter a list of files ?

• Using grep

This command below gives you all files in the current directory which begin by elfutils

dir | grep -i elfutils

elfutils-0.137-3.el5.i386.rpm
elfutils-devel-0.137-3.el5.i386.rpm
elfutils-devel-static-0.137-3.el5.i386.rpm
elfutils-libelf-0.137-3.el5.i386.rpm
elfutils-libelf-devel-0.137-3.el5.i386.rpm
elfutils-libelf-devel-static-0.137-3.el5.i386.rpm
elfutils-libs-0.137-3.el5.i386.rpm

• find can do it recursviely

Remove a file?

Permission: In UNIX and Linux, the ability to remove a file is determined by the access bits of parent directory

chmod 777 .
chown hi-adm:hi-adm .

With the command rm

Example:

• Basic

rm filename.extension

• Prompts for confirmation before removing a file

rm -i filename.extension

• Force removal of the file regardless of it bieng write-protected or open

rm -f filename.extension

• Remove files recursively in 'directory'

rm -r directory

More … perform the man commando

man rm

Copy 1 or multiple file

cp - Copy one or more files to another location.

Example::

• Copy of a directory with resistivity:

cp -r dirtocopy newdir

• Copy two files

cp myFile1.txt myFile2.txt myDirDestination

• Copy all files of directory

cp * myDirDestination
# or
cp /myDirSource/* /myDirDestination

• Copy all txt files (with a pattern)

cp *.txt myDirDestination

Move / Rename

• mv - Moves or renames file

Example:

mv file.log file.$(date "+%Y.%m.%d-%H.%M.%S").log

Concatenate

cat file1 file2 > finalFile

# example with cert
cat first_cert.pem second_cert.pem > combined_cert.pem

Transfer

• Linux Utility - Scp (secure copy, remote file copy) command

See the content

• Shell Data Processing - Cat command (short for concatenate),
• Shell Data Processing - Head (Displays first 10 lines of file),
• tail - Displays last 10 lines of file,
• Shell Data Processing - Tac (for reverse output) (for reverse output)
• less and more let you scroll the text files

Search a file by name

• locate - List files that match a pattern.

Locate all file with a regular expression. In this example all file which begin with sp and end up with the extension msb.

locate -r "sp.*\.msb"

• find - search for files in a directory hierarchy with glob pattern

find /my/directory -name myFile.extension
#
find /my/directory -name globPattern

Search files based on time

touch -d '2011-12-31 10:22' foo
find . -newer foo

See all other files in the time section of the find command

Search the content of files

Shell Data Processing - Global Regular Expression Print (GREP command) (line filtering, word search)

• For the current directory .

grep -rn "string*" .

File Architecture (32 or 64 bit)

File Architecture

file fileName

Example:

file java

/bin/java: ELF 64-bit LSB executable, AMD x86-64, version 1 (SYSV), for GNU/Linux 2.6.9, dynamically linked (uses shared libs), for GNU/Linux 2.6.9, not stripped

Iterate / List

The ls pattern does not work in a bash script unless an option is on.

The best way is to use find when you need pattern matching

ENV_FILES=$(find . -maxdepth 1 -type f -name $ENV_FILE_PATTERN 2> /dev/null)
for ENV_FILE in $ENV_FILES ; do
    echo $ENV_FILE
done

Executable Capability

A file may also be an executable one and it may got capabilities such as being able to take the port 80

On Linux, see:

• setcap - set file capabilities.

sudo setcap 'cap_net_bind_service=+ep' /path/to/your/executable

• getcap - get the file capabilities.

sudo getcap /path/to/your/executable

Processing

• How to read a CSV or a INI file with Bash

Conditional Expression

bash conditional expression on file ¹⁾

-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 set-group-id 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 set-user-id bit is set.

-w file
True if file exists and is writable.

-x file
True if file exists and is executable.

-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.

-O file
True if file exists and is owned by the effective user id.

-S file
True if file exists and is a socket.

file1 -ef file2
True if file1 and file2 refer to the same device and inode numbers.

file1 -nt file2
True if file1 is newer (according to modification date) than file2, or if file1 exists and file2 does not.

file1 -ot file2
True if file1 is older than file2, or if file2 exists and file1 does not.