Find Stuff in Linux

There are four basic commands to find stuff in Linux:

1. whereis
2. which
3. locate
4. find

Searches for binary files, source files, and man pages for the specified command names. Switches:

• -b searches for binaries
• -s searches for source files
• -m searches for manuals

Examples:

whereis ls     # lists binaries, source and manuals if they exist
whereis -b ls  # lists only the binaries
whereis -s ls  # lists only the source files
whereis -m ls  # lists only the man files, if they exist

Returns the path to the executable indicated.

Example: If you want to know which version of Python is called when you type in “python” at the command line…

which python

Fast way to search for files by name on your disk.

Important: Update the database before first locate and after significant changes on your disk.

updatedb  # as root

locate will match the pattern you give it. So you may need to pipe to grep or provide a more specific search patter. Example:

locate python  # locates all file names that include 'python'

find /path/to/search/ -name searchTerm
# 1. The first part is the 'find' command itself
# 2. The second part is where to start searching from
# 3. The third part is an expression that determins what to find
# 4. The fourth part is the name of the file to find

If you get a bunch of garbage on the screen, send stderr (by its file descriptor number: 2) to /dev/null:

find /path/to/search/ -name searchTerm 2>/dev/null

https://www.cyberithub.com/find-command-in-linux/

The -exec flag to find causes find to execute the given command once per file matched, and it will place the name of the file wherever you put the {} placeholder. The command must end with a semicolon, which has to be escaped from the shell, either as \; or as “;”.

Syntax to be used for find exec multiple commands:

find {PATH} [OPTIONS] -exec {COMMAND} {} ;

The first argument after the find command is the location you wish to search. Although you may specify a specific directory, you can use a metacharacter to serve as a substitute. The three metacharacters that work with this command include:

• Period (.): Specifies the current and all nested folders.
• Forward Slash (/): Specifies the entire filesystem.
• Tilde (~): Specifies the active user's home directory.

Find all files (not directories or links) of 1033 bytes in size that are not executable and which can be read (i.e., you can cat the file and read the contents):

find . -type f -size 1033c ! -executable -exec cat {} \;

The first argument after the find command is the location you wish to search (the starting point, and find will recurse into subdirs).

• You may specify a specific directory path, or
• You can use a metacharacter to serve as a substitute.

Three metacharacters that work with this command include:

1. Period (.): Specifies the current and all nested folders.
2. Forward Slash (/): Specifies the entire filesystem.
3. Tilde (~): Specifies the active user's home directory.

This specifies how we want to match what we are looking for.

Most common: -name (searches for the name you provide of a file or folder).

find / -name file.txt   # specify exact name
find / -name 'file1*'   # use search patterns
find / -name '*.txt'    # use search patterns for extentions
find / -iname 'FILE.txt # use iname for a case-INsensitive search

Other expressions to use…

Use the -type expression. The most common is “f” for file but the others are just as easy:

Examples:

find . -type d               # find only/all directories, recursive
find . -type f               # find only/all files, recursive
find . -type f -name '*.txt' # find only/all files named with txt extension

Use the -size expression. All units are rounded up (this is tricky!), for example, 1M = 1048576c but:

• -size -1M will find only empty files (because anything less that 1 is 0, therefore this will match only those files less than 1, which is 0M).
• -size -1048576c will find files from 0 to 1,048,575 bytes (i.e. 0 to one byte below 1M).

Example:

find . -type f -size +50c  # find all files larger than 50 bytes
find . -type f -size 510c  # find all files exactly 510 byes

Use the –user expression and provide the username or user ID (uid). Examples:

find . -type f -user greg

Use the -perm expression. There are three ways to specify perm mode:

1. No prefix: find exact permissions
2. Prefix of '-': find “at least” permissions (not exact)
3. Prefix of '/': find permission in either owner, group, OR other

Examples:

find . -type f -perm 664 
# find files with exactly 644 perms in current dir and all subdirs

find . -type f -perm -664
# find files with "at least" 644 perms (and more)

find . -type f -perm /222
# find files writeable by somebody (owner, group, OR other)

find . -type f -perm /220
# find files writeable by EITHER owner OR group (but no one else)

find . -type f -perm -220
# find files writeable by BOTH owner AND group (but no one else)

find / -perm /4000 -type f -exec ls -ld {} \; 2>/dev/null
# This will find files with the SUID bit set.
# -l long listing format
# -d list directory names, not contents

You can find files by modification, access, or change in timestamps.

Three timestamps for DAYS (24-hour periods):

Three timestamps for MINUTES (60-second periods)

Note: Any fractional part of the time period is ignored. Therefore -atime +1 will find files accessed TWO days ago or longer (because files accessed today, or within the last 23.99 hours, can be found with atime 0).

Examples:

find . -type f -mtime -10
# find all files modified less than 10 days ago
# find all files less than 10 days old

find . -type f -mtime +10
# find all files modified more than 10 days ago
# find all files older than 10 days old

find . -type f -mtime 0
# find all files modified today